Who has one? how much of a difference do they make?? I am purchasing one in the winter a 12.7mm stroker crank for one of my bikes and i am wanting to know what will come out of it... how many hp does it gain? top end gain? tourqe gain?? so for anyone that has crank modds please post! thanks

 

I bought a Wiseco crank to go with a 89mm (440) Wiseco kit. Have yet to drop them in .... but even thought the crank and piston say 12:5:1, the guy I spoke with said its actually 12:6:1 on the ratio's. He said a stage 2 cam and some valve adjusting would make it tough. Add in a bigger carb and some porting to the valve set up and he said hold on.

One more thing. Honda makes an after market timing chain that is thicker than the stock. They usually run about $95, but I snagged one on eBay for about $60.

 

I have a 250x... It has extensive work done so far and this is the absolute last thing i can do! it has the bigbore kit and ported/polished cam raised the compression, new everything bigger valves the works! im just looking for more LOL hope this is what i need for the track! right now im out running 400's with it and looking for some 450's! not counting on it but looking for it i love the sleeper look! I want so much tourge out of it i cant hang on to the bike... So a 12.7mm stroker crank and a weighted flywheel and a rev box should set me off!

 

What ratios are you running on your sprockets? Guy up the road has a Z400 and if he is running alot where he is in his top 3 gears, he'll bump up his front and drop the rear. Does the opposite for the trails. He said it takes him about 10 minutes to swap'em out.

Well I guess the crank is the last thing you need. Ever think about blue printing the engine and balancing it?

 

I have never herd of blue printing the engine and balancing it... please explain... I run a 14/38 gearing all the time i have found its best for my bike in every situation but in really short tracks where i need tourqe i am running a 12/38 gearing

 

Blue Printing on an engine is done alot in race cars. When you have 8 cylinders going 8 different ways ---- you get alot of diffetrent things happening at once.

Blue printing puts everything right at spec. If the piston is supposed to weigh 6oz, you machine and balance it to exactly 6oz. When an engine is designed, everything has an exact purpose. This crank will weigh this much and spin this fast and have this much inertia. With that said, a piston and its properties are matched against the valves and the cam etc. Trickle down effect. To get the specs of the parts in your engine will take some digging but its not hard. most after market manufactures will give it to you.

A friend of mine works in a shop that has a roller dyno. Pull your vehicle on and rev it up. He had a local motorcycle club come through and a guy brought in a Hayabuisa pretty much right off the showroom floor. It was around 150hp at the rear wheel (if memory serves me correctly) He blue printed, did some exhaust work etc and when he brought it back it was just under 200hp. he did put after market parts in because of their durability, but everything was blue printed.

When you are turning 8000 rpm, you MOI starts to get up there as well. The easiest way to describe MOI is like having 1 brick on a 12inch string and 1 on a 36 inch string. If I asked you and another guy to spin each one as fast as possible, stop and then start again, the guy with the shorter string would have an easier time. Same goes for an engine. When you stroke it, you are definately getting more out of it ..... but you are also "spinning the brick" so to speak on a longer piece of string. So every little bit that you can shave here and there will add up.

Another big mistake that I see is carbs. Young kid where I ride has a Honda dirt bike .... like a 170 or 180. His dad and him did a project where they put a larger diameter piston and a different cam .... but failed to get more air in. They were even running a stock filter. Another guy that rides a RM250 noticed and helped ...... the bike is pretty damn quick now. So get lotsa air in there. Valve settings as well will help.

The guy I mentioned with the RM250 is the same one that I mentioned about the sprockets. I want to say when he is not looking towards the power side, he runs a 16/34 or 16/36. He had the rear made at the machine shop on HWY 210 here locally

 

enough said with the blue printing, i was gonna say the same thing but i wasn't sure if it was possible to blue print a small engine such as and atv engine. all i can say is d*** that! if your out runnin 400's with a 250x. i had one a few years back and their pretty quick but geez i didnt know they could be turned into such a beast! lol! what is done to the 400's tho? are they up to the same level as far as go fast goodies? cuz if they are then ima have to see that to beleive it not sayin your a liar by anymeans but d***, thats incredible.


anybody live around the aonia pass area near washington, georgia? or have any information on how and when and where to get into dirt track or TT racing an atv close to augusta georgia?

 

the 400's are stock.... but i have more tourqe and smooth power than them and i can still race in a lower class.. If you want everything i have done then i will Pm you

 

Oh ok that makes more since. you know where washington georgia is 1988fast250x?

 

no i dont know where that is at.. how far away is it from cartersville?? or do you know?? We also have a 87 lt250r, 94 blaster, 2001 blaster, and a big bear 350 4x4 fixing to get a 400ex and a 300 fourtrax 4x4 We bring alot of fourwheelers in and turn them out for fun,, take em in clean them up and send them on to the next buyer,, But the lt and the blasters are here to stay untill we get the 400ex and then were selling one blaster,, also i dont like 4x4's so there out the door as soon as there nice and ready to go! make a pretty good profite