Home Forums 2-Cycle Racing KPV issues?

Tagged: 

This topic contains 21 replies, has 8 voices, and was last updated by  Brock Weiss 2 years, 5 months ago.

Viewing 22 posts - 1 through 22 (of 22 total)
  • Author
    Posts
  • #49302

    Brock Weiss
    Participant

    I have a issue with my KPV engine that I have no idea what to do on

    i switched engine builders this last year from a very good engine builder to one of the best engine builders. I don’t want to name names because I don’t know if something is wrong or not? So I don’t want to be badmouthing an engine builder if it isn’t their fault.

    Anyway last year  I was getting RPMS with no problems and was a lot faster and had no issues with competitive lap times.  This year I decided to switch engine builders and went with one of the top guys in karting and the issues I have is this year I have a hard time getting the RPMs I was getting last year and I’m about .5 seconds slower than I was last year.

    Is there a reason for this that I’m missing and is there anything I can do to try and get my RPMS back to where they were last year? Does anyone have any tips on how to increase RPMS or did this engine builder build it differently? I sent it back to the engine builder and he said there is nothing wrong with it and in fact he said the Dyno is getting 24 HP. I would think I would be able to get the same RPMS and lap times that I did last year with that much HP then. The engine does seem to run good but I just don’t understand the drop in RPMS and Lap times

    my numbers for last year averages are

    Max RPMS-14800

    Miniumum RPMS -7200

    This year averages are

    Max RPMS- 14100

    Minimum RPMS-6500

    If anyone has any suggestions on what I can do to get more power or to get my RPMS up it would be much appreciated because I just don’t understand why the difference especially when I had one of the best builders rebuild it this time around

    but like I said I had no issues getting 14700 RPMS last year and this year I think I hit it twice and I’m about .5 seconds slower

    if there are any tips on how to increase the RPMS I would appreciate it

    Thanks

     

     

     

     

    #49384

    TJ Koyen
    Moderator

    Hey Brock,

    Are your carb settings correct? Is the track condition the same as you ended on last year? Have you tried simply adding teeth?

    Driver/Coach/Wrench : Innovative Performance/Exprit
    Owner : Oktane Visual - www.oktanevisual.com
    www.facebook.com/oktanevisual
    www.instagram.com/oktanevisual

    #49434

    Gary Lawson
    Participant

    Are you running the same gear ratio, tires compound and size, chassis, and flex length as last year? If you are then it’s likely the engine builder didn’t do a very good job. 700 rpm is about 3 mph! That would add up to a half second pretty easily.

    #49435

    Gary Lawson
    Participant

    Noticing your minimum rpm are also off by about 700 it seems like you may have a different gear on it. I’m guessing you have an 11 tooth on the clutch now and last year you had a 10.

    #49474

    Brock Weiss
    Participant

    Here is what I know. I have the same driver 10 tooth as last year, same tires, same flex length, same carb settings, same gearing ratio, and the track conditions are about the same as I looked up the times we ran last year and weather as I keep detailed data.

    TJ my carb setting are 1/4 high and 2  1/4 – 2 1/2 low which is what the engine builder said to run

    Gary we were running a different chassis this year again I would rather not say what we went to in case it isn’t the chassis that is the issue.  However we ended up switching back to OTK  which is what we ran last year we had a 2012 Kosmic Kart and we went back to a brand new 2014 Tony Kart EVK  and the times got better but we are still off by .5 seconds. From what I can tell the driving looks good no different than last year but we just can’t get the RPMS

    The only thing that is different is the engine builder but again the builder I used is probably one of the top three builders in the country so I just don’t get it as I also put three other people in the kArt and they had a hard time with attaining The proper RPMS just so I could eliminate the driver

    like I said I even sent it back a second time and the builder sent me a Dyno sheet that said it was getting 24.5 HP with the peak at 13100…… And said the engine is top notch but I just don’t get how we are slower and we can’t get the RPMS that we used to especially when he tells me it has 24.5 HP which seems like a lot for a KPV

    I bought another KPV engine as a backup and sent that in to Comet racing engines so Brandon can do a complete rebuild on it but he won’t have it done until middle of June and I have 2 more race weekends before I get that one back so I’m trying not to get killed in the points until then.

    I figure if we get the Comet Engine back and we all of a sudden start winning again and get our RPMS and speed back then there is my answer. engine builder didn’t do his job but if we get the Comet Engine back and we are the same then it is the driving that fell off or something else

    It is just frustrating when you don’t know what the heck is the issue. I guess the thing I will have to do is wait until I get the other engine back  and see if we pick up speed and RPMS Because I have tried everything else. Although I’m sure it could be a million other things as well.

     

     

     

    #49476

    Jim White
    Participant

    Did the new builder rebuild the carb too? You say you are running his settings but how do those compare to what you used to run? A slight change in pop off can effect the needle settings. I’ve only run a walbro on a Yamaha but it was never a set it and forget if you wanted to be fast. I’d be looking there. Slightly rich will kill RPM’s every time.

    #49477

    TJ Koyen
    Moderator

    Do you run EGT temps on your engine Brock?

    Driver/Coach/Wrench : Innovative Performance/Exprit
    Owner : Oktane Visual - www.oktanevisual.com
    www.facebook.com/oktanevisual
    www.instagram.com/oktanevisual

    #49482

    Brock Weiss
    Participant

    TJ yes I run a EGT sensor and it is usually around 1000-1050 area. I’m not sure what to do with those readings I just know you don’t want it in the 1200 range.

    Jim yes the engine builder rebuilt the carb and I also bought one of his as well.  Last year I ran 1/8 high and 2 1/4- 2 1/2 low.

    This year I have tried that but we were slower as I think the engine builder runs his richer because it does seem to have more power when I follow his carb settings. I have tried 1/8 high and 2 1/2 and we were slower so my data shows we have been fastest with 1/4 high and the 2 1/4 low..

    I will Check more into the pop off thing and see if that is correct as I have the guy at the track rebuild the carb after every race weekend but he only does the gaskets and such not a full rebuild so I will ask him about the pop off tomorrow before our race

    could fuel be an issue? I run 110 octane fuel that they sell at the track instead of the 98 fuel but I was running the same fuel as last year. Should I try and switch to the 98 or will that not do anything?

    We are going out again this weekend for races so I will try and take extremely good notes and I will have a couple of people drive it Again and see what they get for RPMS and will compare that to what we run but like I said in my previous posts they also struggled to get over 14300 for RPMS and the engine builder said we should be able to get 14700 easy  for this motor and pipe and last year we even got 15000 RPMS a couple of times and almost always got over 14600 without blinking an eyelash

     

    #49483

    TJ Koyen
    Moderator

    Start adding teeth. If you don’t pick up RPM by adding teeth, then you’ve got some kind of issue on your hands. Until then, it could be anything.

    Driver/Coach/Wrench : Innovative Performance/Exprit
    Owner : Oktane Visual - www.oktanevisual.com
    www.facebook.com/oktanevisual
    www.instagram.com/oktanevisual

    #49490

    Brock Weiss
    Participant

    TJ

    i tried adding teeth today and we went from 14000 max rpm and 5000 low rpm to about 14100 max rpm and 6500 low rpm but we were slower because we got passed on the straights because it was a higher speed track layout.

    The he leader is running a 76 for gearing and he is getting 15000 rpm and when we try the same gear we get 14100 max rpm.

    I’m just at my wits end on this karting stuff.  Especially when last year we had no issues at all with lap times or getting RPMS where this year we can’t get any speed at all.

    Is it possible to just lose your karting ability? The reason I say this is a sent the motor back to this engine builder and he swears it is a strong running motor and it is getting 24,5 HP on the DYNO.  Which you would think with that kind of  HP on a KPV we should be faster than what we are and the engine builder said we should be getting 14700 RPMS easy.

     

    Problen is is we are not and that is where I’m confused as hell. I have had people watch Blake and they said he seems to be racing just fine

    #49516

    Patrick Haney
    Participant

    Could it be harmonics? Crank out of balance? Twisted? It sounds like you covered all of the bases in trying to get the highest rpm’s and the engine builder got 24 hp at 13k but did he get it to 14700 under load?  Is the pipe clogged?

    #49518

    Stu Hayner
    Participant

    I knew a guy that quit karting because he couldn’t get any of his 3 hpv engines to run correctly after having them all professionally rebuilt.

    Even though he has never come back to karting, he did find the problem. He had put a rag in the pipe opening to keep anything from going in.

    All three engine just “ran like crap”.

    Try a different pipe before you give up.

    Stu

    #49521

    Brock Weiss
    Participant

    First off I want to say thank you to everyone that posted on here trying to help.  I really appreciate it and all your suggestions really helped as I tried all and I think I found the problem.  I was able to eliminate all the potential problems by trying all of your suggestions however this weekend I was still getting Min RPMs of 5500 and Max RPMs of 14100.  Needless to say we lost this Saturday in racing again by  mile.

    However I was able to borrow a friends Carb because he said it could just be a crappy carb.  I never though about that because I bought one new carb and had the other one rebuilt by the engine builder.

    Anyway I used a friends Carb that was rebuilt by Brandon from Comet Racing Engines and all of a sudden I gained about 400 RPMs Like Magic and we won our first race! The RPMS went up to 14650 max RPMS and was able to lead the whole race. I will have to do more testing this week to make sure they was the issue but it looks like I will be calling Brandon from Comet Racing engines and buying me some Carbs!!

     

    it was amazing the difference in RPMS we gained just by trying the Comet One.

    Quick question, can anyone explain how you adjust your carb at the beginning of the race? I have seen people do that and I have heard it is very important I am just not sure where you would start your needles and what you adjust once the race starts? I think you start your LOW at 2 and then adjust it to 2 1/2 when the green flag drops?

    if someone could explain how do this I would appreciate it as I want to start learning this technique

     

    thanks again for all the replies and let’s hope I found the issue.  Bad carbs?

    #49524

    TJ Koyen
    Moderator

    Glad to hear you figured it out.

    Carbs are weird, we have had some carbs in Leopard that run great on one engine but terrible on another engine. And we have had other carbs that run great on all engines.

    For the KPV, we start the carb at 1 1/2 on the low and and little under 1/4 on the high. As you start accelerating for the green, open the low up to your race setting of 2 1/4 or whatever you run. The carbs on those engines flood out really easily in low RPM and it can make them sluggish off the line. Leaning it in like that keeps it crisp when you accelerate from low-speed.

    I remember a few races in HPV Jr. years ago at South Bend where I was leaning the carb back down as I came into the hairpin every lap because we were really sluggish off that corner.

    Driver/Coach/Wrench : Innovative Performance/Exprit
    Owner : Oktane Visual - www.oktanevisual.com
    www.facebook.com/oktanevisual
    www.instagram.com/oktanevisual

    #49554

    Tim Koyen
    Participant

    Some builders set their carbs up to run with the high completely closed, some like it cracked open, and others like it open even more.  Be sure that you and your builder are together on what the proper settings are for your carb(s).  And just because the carb settings were at one setting this weekend, doesn’t mean they will be exactly the same next weekend.  The air quality plays a big factor in the carb settings, as well as what gear you are able to pull.  When the air is crisp and dry, you may be able to run a very small rear gear, but the next weekend, they weather may be entirely different, and may require 3 more teeth to get the same RPM.

    Also, don’t get fixated on what RPMs you’re turning.  Every engine is a little different.  Some like have a higher power band, and some lower.  I’ve seen guys running identical lap times with a 500 RPM difference between them.  I’m not saying that you should disregard the Tach, just don’t rely entirely on that to tell you where to go from here.

    This is slightly off topic, but I see that you’re a Data Guy…  Karts can only be properly tuned on the track; based on the conditions of the day.  Grip level, tire condition, weather, fuel, and driver condition are all factors that go into getting everything just right.  You can’t look at a chart, set the kart up at home, and expect to have it perfect when you hit the pavement.  Get a baseline setup, turn some laps, and see what the conditions of the day warrant and what the kart wants.  Data will help you get that baseline, but you do the rest of the work at the track.  That’s the FUN part!

    KartLift Kart Stands
    DeepSeat Kart Seats
    877-777-8020
    ------------------
    Don't bother PMing me, it doesn't work. Email is best: tim@kartlift.com.

    #49570

    Brock Weiss
    Participant

    Thank you to everyone that weighed in here.  This is only my second year in KPV and third year in karting and I have learned a lot but I have so much more to learn.  Special thanks to Tim Koyen about tou can’t set the kart up at home and win the race in the garage.  My son actually is the driver and I’m the so called tuner and sometimes I think I’m trying to win the race for him and as a parent it is hard to not do that but It made a lot of sense with you cant win the race in your garage

    Now if only I could remember where I heard that before? The words TJ come to mind! But seriously it makes a lot of sense and I have to force myself to follow that advice.  It is an easy trap to fall into some times for me

    #49571

    Gary Lawson
    Participant

    I personally would not trust an engine builder that tried to tell me my kpv engine made 24 hp. And if you had two carbs from this builder and neither would run worth a darn then how did it dyno so well? To pick up 400 rpm you basically picked up a full horsepower! So now I guess it makes 25.5 hp? You Could race that engine in Tag I guess 🙂

    #49579

    TJ Koyen
    Moderator

    I agree with Gary. KPVs don’t make that much power. It’s easy to make a dyno read whatever you want.

    I would also note that if you are having engine problems and your engine guy just says “it should be fine” but doesn’t help you troubleshoot your issues, then you might want to look somewhere else.

    Driver/Coach/Wrench : Innovative Performance/Exprit
    Owner : Oktane Visual - www.oktanevisual.com
    www.facebook.com/oktanevisual
    www.instagram.com/oktanevisual

    #49613

    Walt Gifford
    Participant

    You say you started running high octane gas? that will retard your spark. Did the new builder use the same ignition timing? Don’t ignore getting your pipe cleaned.

    Since the engine builder hasn’t been mentioned yet I can say in general the best builder might not do his best for you if you are not one of his golden boys that are out there building his reputation and what makes them the best might just be the best BS.

    A new or unknown customer usually gets a safe ignition timing and lots of piston clearance so they don’t stick the piston and blame the builder. If it’s slow the builder can blame many things and back up his engine build with doctored dyno sheets that make outrageous HP claims.

    I knew a guy that always talked about his dyno tuning, had dyno sheets on everything. Years later I found out he didn’t even have a dyno.

    I had a customer bring me an engine from the best builder around here he scuffed the bore, put in a new ring and called it a total blueprint he’s best because he charges the most. Lot of BS in karting.

    Gif

    FAA certified jet engine and aircraft technician,
    Nicholson Speedway class champion 2001,
    Yamaha KT100 Service Center,
    41 years karting experience

    #49773

    Brock Weiss
    Participant

    Again thanks for all the replies.

    Walt I have a brand new Pipe this year that I use only for racing so it should still be good plus i also used my other pipe from last year that I clean on a regular basis but that is a good suggestion so thanks.

    We will find out this next weekend if in fact the engine is the problem as I just got my second KPV Engine back from Brandon at Comet Kart Sales  as I did do what TJ suggested and found a different builder and Brandon seemed like a stand up guy and he didn’t charge me $1200 to rebuild it like this other builder did so I figure if we go faster and have no issues getting RPMS on that motor then we know the issue is the motor because I’m going to do a back to back test. If we go the same lap times and have the same RPMS and such the  we know somehow the driving went south.

    Gary I agree with you on the HP think 24.5 seemed crazy to me as well. I even doubled checked it this morning and it it said peak HP 24.5 at 13100 RPMS. They just seemed unbelievable to me as I thought the KPV engine got only 20 HP on average I just was amazed since this is a top builder and seems highly respected in the karting community but sure enough it says it right on the Dyno Sheet 24.5 HP at 13100 peak RPMs whatever that means

    Walt your right about the new customer thing. I probably messed up when I told the engine builder that we have only been karting for three years and we run at the club level  And that next year I wanted to move into the regional scene and then he national scene as I just didn’t want to throw my son out there in the big leagues until he was ready so he wouldn’t be a danger to other kids and so he also could hold his own against the other junior drivers but perhaps the builder did just what you said as I did tell him that I don’t have a lot of experience in the KPV engine and that I was still learning how things worked. So perhaps by me saying that to him he did build it safely but that really would sucked if that is what he did.

    Even though we have been in karting for three years we have been successful in the short three years that we have been running. Last year we almost won the championship and was the runner up in his division and the year before that he took third in his class and he did this racing against kids that had triple the experience so we have been running well up until this year but unfortunately this whole engine thing has killed my sons confidence as he thinks he has lost his driving ability. He is 13 years old so he doesn’t still fully understand how engines can change from one builder to the next based on how they build it. Hopefully with the Comet Engine we will get our speed back and confidence and still have a shot to win the championship as we still have 11 races to go this year.

    it just will make me extremely pissed off if I put that Comet engine and the thing is a rocket compared to this motor especially when I sent this motor back to the engine builder and he said everything is fine and it was a strong running motor  but like I said I didn’t want to name the builder yet until I can have more concrete evidence that it is in fact the motor and not his driving that has regressed for some reason as I want to be fair to the builder if in fact it is his driving but we should know after we take the Comet engine out and can compare

    Anyway very good discussion on this and I’m greateful for all the replies

     

     

    #50300

    Brock Weiss
    Participant

    So we had our race this weekend and wouldn’t you know my son ended up taking P1 yesterday and P2 today.  We almost won again today but missed it by about 7 inches that is how close it was.

    More importantly, we used our new KPV engine that Brandon at Comet Kart Sales built for us and the thing was a rocket!

    we went from 14200 RPMS to 14800 just by switching engines.

    I think the thing that makes me mad about this whole deal is that I called the engine builder in question and told him my issues with motor and even sent it back to him telling him no matter what we did we could not get over 14200 RPMS  and he sent it back saying it was perfect And there was nothing wrong with it And it was us for some reason even though I told him I had three other people drive it and they also couldn’t get RPMS

    Well today proved that there was something wrong with it because we gained 600 RPMS using The Comet built motor and won yesterday and took 2nd today.

    I just upsets me that I was charged $1200 for a rebuild and all I got was a pile of junk from supposedly one of the best engine builders in karting right now. You would think they would stand behind their work and still build a top level engine even for club racers

    At least I have a new engine builder in Brandon and Comet Kart Sales as he really built a good engine for me and didn’t care if I was a club level guy or a national guy.

    Needless to say I’m sending this other engine into Brandon to have him fix it and do a complete rebuild on it as he was also half the price of this other engine builder.

    Alright im done being aggravated by this whole deal as at least I found a solid engine builder now that I can trust and will be sending all my engines to in the future

     

     

    #50301

    Brock Weiss
    Participant

    So we had our race this weekend and wouldn’t you know my son ended up taking P1 yesterday and P2 today.  We almost won again today but missed it by about 7 inches that is how close it was.

    More importantly, we used our new KPV engine that Brandon at Comet Kart Sales built for us and the thing was a rocket!

    we went from 14100 RPMS to 14800 just by switching engines.

    I think the thing that makes me mad about this whole deal is that I called the engine builder in question and told him my issues with motor and even sent it back to him telling him no matter what we did we could not get over 14100 RPMS  and he sent it back saying it was perfect And there was nothing wrong with it And it was us for some reason even though I told him I had three other people drive it and they also couldn’t get RPMS

    Well today proved that there was something wrong with it because we gained 700 RPMS using The Comet built motor and won yesterday and took 2nd today.

    I just upsets me that I was charged $1200 for a rebuild and all I got was a pile of junk from supposedly one of the best engine builders in karting right now. You would think they would stand behind their work and still build a top level engine even for club racers

    At least I have a new engine builder in Brandon and Comet Kart Sales as he really built a good engine for me and didn’t care if I was a club level guy or a national guy.

    Needless to say I’m sending this other engine into Brandon to have him fix it and do a complete rebuild on it as he was also half the price of this other engine builder.

    Alright im done being aggravated by this whole deal as at least I found a solid engine builder now that I can trust and will be sending all my engines to in the future

     

     

Viewing 22 posts - 1 through 22 (of 22 total)

You must be logged in to reply to this topic.

Karting's News and Information Leader ekartingnews | an HMG publication