Motor build ideas?

ekripper · Dec 9, 2006

Well, since winter has set in here I need a winter project. I have my 70 chassis almost the way I want it now and I'm itchin to build a bad ass Honda based motor for it. My GPX is working great and will get me through the winter on the indoor track so I want to take my time and build a nasty motor for summer on the big bike tracks and have a few questions for you guys that have done some Honda builds.

I really like having a four speed tranny especially riding the big tracks. Is it possible to run the CHP close ratio four speed tranny with the new Takegawa special clutch that uses the stock output shaft? If this won't work, any other thoughts on what to do for a four speed/manual clutch setup. I don't want the Daytona as I am not a fan of 1d 3up and my buddy has one and has had nothing but trouble with it. Not saying it's bad but that's my only exposure to it and watching him try to find neutral on his $1000 tranny so he can restart his bike is not something I am interested in.

As for the top end, I am debating between the Tak +R setup or the Daytona 119 DOHC. The price of the Daytona is quite frightening and that alone makes me think twice about it. A couple of my buddies have the Tak 138 +R's on their 110's and those seem to be sweet motors with sick power. I think I've read on here somewhere that PAX racing can stroke the 124 SE and 124 +R cranks and get them to 131 or something like that. Anyone here know much about that, such as the displacement, cost, and who does it for sure? I really want to be able to run with my buddies on their 138R's. So what are your guys opinions between the R and the Daytona DOHC? I would think at half the price and if you could get displacement to around 130 on the R set up it would be a runnin son of a B!

Last one would be carb. 28 or 26 mil. carb on either of those motors? Your guys opinions are much appreciated. Thanks.

slowracer · Dec 9, 2006

I would have finch build you a jailing 160 or a honda nice with a +r head.That would cost you lass than my dohc top end and would make way beter power delivery

ekripper · Dec 9, 2006

slowracer said:
I would have finch build you a jailing 160 or a honda nice with a +r head.That would cost you lass than my dohc top end and would make way beter power delivery

slowracer, how is the power delivery on your DOHC? Is it pretty much mid to top end power? That is one thing I will say about the 140 GPX setup, it pulls very strong off the bottom all the way through the mid. It does sign off a bit early though. I was thinking of going with the 146 kit, having my Lifan big valve head ported and of course going with a bigger 26mm carb. I think this would let it rev a bit more and keep the same power delivery.

slowracer · Dec 9, 2006

The dohc lacks the botom end compared to a motor with a 57 mill crank,Mines only a 52 so you can feel the difference.My buddy matt has a 124se with a 57 mill crank and that thing has so much more botom end than my motor,It's much easer to go faster on his than mine.

Going with a set up like you have finch has shown 17 hp with a great torqe curve so I dont think you could go wrong with that set up.Just make sure you have someone good do the head.I have a friend that does NHRA prostock motorcycle stuff and he did a head for me on a gpx 131 and that motor kicked ass over a crower head 131,so just make sure it's somebody good thats going to do the head

ekripper · Dec 9, 2006

good point about the power curve. I think I'll try the 146 setup with a good port job and see how it feels before I get to deep into a Honda base build.

boxy · Dec 9, 2006

honda 124 super+r and get yourself a taky 5 speed + clutch and set it up with a kx85 29mm carb.

Should do the trick!

slowracer · Dec 10, 2006

boxy said:
honda 124 super+r and get yourself a taky 5 speed + clutch and set it up with a kx85 29mm carb.

Should do the trick!

5 speeds go KABOOM in the dirt with a 10" wheel let alone a 12

Z50King · Dec 10, 2006

i think you should try to make a desmodromic valve system

uno4cinco · Dec 12, 2006

Honda Nice motor is way to go. 4 speed, strong bottom end. you can build them up to 190 for street and like 175-180 for dirt. You can put R heads, DOHC heads and reworked TJR heads on them. alot of motor builders have been telling me you can get 22+ hp out of one. Im getting on and doing a 154 kit that should put right around 20. Contact RJP racing 408-245-4888, hes also an advertiser on here. He can give you some more info on them. They will cost about the same as a Daytona motor too.

matt-tastic · Dec 12, 2006

well, ya, the jailing cranks are larger..the "stroker" motors are most likely a chinese crank w/ a chinese bottom end....which isn't all bad...if you build it right...you could do a 124se w/ the take or kitaco clutch...and a chp 4 speed....or...you could get an extreme motor, put a kitaco or takegawa top end on it, and use the new "cooper" tranny...it seems to work well too...

ekripper · Dec 13, 2006

Well, I decided to try out the Cat5 setup on my GPX first. I ran it with the 140 kit this summer and it worked pretty well. I have been very impressed with the tranny thus far. From the sounds of it the Cat5 146 kit should work pretty well. I'm going to run this for awhile and see how I like it. If I end up wanting more, I may end up doing a nice motor. In all honesty though, the only place I could see wanting more would be on the outdoor big bike tracks and even then it's questionable. At Xfest, my 140 pulled very well and I finished mid pack in the vet class with some very built 110's. So, if I'm honest with myself, I would say at this point I'm lacking riding skill and not so much motor. For me, it's more of a hang up with having a chinese motor in such a sweet chassis, but I can't seem to find any fault at all with the GPX power or reliability wise. I'll let you guys know how this motor is when I get everything back together after christmas.

Motor build ideas?

ekripper

slowracer

ekripper

slowracer

ekripper

boxy

slowracer

Z50King

uno4cinco

matt-tastic

ekripper

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