December 31, 2015 at 3:40 pm #58707
I’m new to karting, and bought a used Birel RY30 and a new LO206 for my son to race JR Briggs (restricted) this year. I’ve read that you want weight distribution to be about 42% front/58% rear and 50/50 left to right in general for sprint karts.
We weighed his kart and it’s about right front to back, but has significantly more weight on the right than the left (I’m assuming because of the engine). Is this the norm for 4 stroke karts since they don’t have a battery and radiator on the left? Should I add ballast to the left? Also, is the 42/58 front to rear distribution correct for the lower power 4 stroke karts?
Thanks in advance for any advice!
January 1, 2016 at 8:07 am #58722
- This topic was modified 1 year, 1 month ago by David Keadle.
Not uncommon. How much does your son weight? Follow manufacture guidelines for seat mounting location. You might want to see if you can move the seat and engine more to the left. Usually as far left as possible. You might still need to add weight to the left side of the seat. Also with a light driver, you will probably need to raise the height of the seat to get the weight higher to get more lateral grip. Front to rear is probably good. Hope this helps.January 22, 2016 at 10:10 am #59815
I also recently purchased, for me and my oldest son of 14 years, a Birel 2013 R30-CY that seems to have the permanent seat struts already off set to fit a 4 stroke (Hondas/clones and Briggs use the same bolt pattern and are very similar in size)… On my other sons, of 10 years, I purchased a cadet Birel 2011 R28, which I cut the permanent seat struts off (were not offset) and found some good moveable seat struts (old school/they way they were done in the past) to offset the seat to the left to fit the motor (any 4 stroke)… you want to make sure you get a good fully adjustable 1/2 inch thick motor mount first… I found one on ebay that is 10 degrees for wheel clearance, seat clearance (look for a narrow simple chain guard too) and chain/sprocket clearance on the back cross member that are now angled (unlike the older chassis in the past that were straight) this makes for a tight fit since all 4 strokes are inboard driven… you don”t want to offset the motor too much (overhang the motor rails) like I see on a lot of karts because of motor vibration, weight balance (your concern!) and chassis flex!… this has been a very big learning curve and experience for me too for the last nine months since I haven’t raced since the 90’s… call me if you would like (Ill send you pics of the mount and struts/chain guard/finished cadet kart) and for more info on where I got the mount and seat struts because I am/was in the same boat your in…
915.478.8482January 22, 2016 at 7:24 pm #59862
I would go for closer to 44/56 front/rear percentage. You will want to fill the left side of the seat up with lead first for sure if you have a smaller driver. Don’t offset the seat too much to the left of you decide to move it. The center of gravity needs to be towards the center of the kart. Let me exaggerate to prove a point. You could mount the seat 6 inches further left and then mount all the weight on the right side of the kart bolted to the frame and the percentages will be “correct” but do you think it will handle well?January 28, 2016 at 9:08 am #60115
don”t offset seat too much because you wont have too… on the 2011 Birel C28 R cadet kart, at the most i offset seat (size small) was two inches (no where near six inches?!?) more than where the permanent seat mounts were… i was able to place all the load on both rails with no overhang of the engine (with the !/2″ thick billet aluminum fully adjustable front to back side to side mount i recommended… about $120 and money well spent!)… you don’t want the engine to overhang due to vibration from the motor and the springboard effect it will have but– you will definitely still require chain/clutch/sprocket clearance since four strokes are inboard driven… the 2013 Birel R30 CY as mentioned before had the seat permanently offset about by (once again) two inches… i had plenty of clearance with about an inch to spare (before clutch touches large size seat)… motor is not dead center on rails but probably overhangs about less than an inch… after all this is done you can now move the seat (with karter in it) or motor front to back to reach a proper balance (as we use to do old school in the 80’s/90″s)… best of luck
nothing better than a day at the races except maybe two!…
- This reply was modified 1 year ago by Ronald Salas.
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