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About that 117cc Kit

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I'm about 2" from ordering the kit and I know a couple of you guys have them. Clue me in on a few things (that's why I was asking clutch/valve questions)...

One, I think I'm going to get STROKER KIT 5, Stroker Kit 5 Link and ordering a cam also.

But here's the scoop - will the 117cc kit run pretty good with the stock CRF/XR70 head? The STROKER KIT 5 doesn't come with a head...

Also I see TB's has a HD 70cc auto clutch. I want the auto because to me that's what makes it a pit bike, and I have a bunch of people that ride my bike that dig the auto... should I go with the TB HD Auto or if you jump over to Classic Honda's site they show an auto clutch they claim has 300% more clamping force - they don't mention the brand. Which clutch do you think can handle the abuse better? I'm sure I'll be replacing plates but they don't really tell you how strong the TB unit is compared to stock.

I'll of course be putting the High Volume oil pump on it, but since I'm not racing it (just play riding a few laps at a time) I was hoping to get away with NOT having to use an oil cooler... any thoughts on that?

Thanks guys it's appreciated.

Mike

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Before you order, see if Mike has any of the OLDER race head pistons available. If so, use that and the 70 head and you'll be set. If NOT, you want the race head as it's got a bigger combustion chamber and valving.

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With that stroker kit, you must ALREADY have a 88cc big bore engine with a race head.

Then you buy that stroker kit, and stroke your already race head engine, into a stroked 117 race head engine.

For anything 108cc's and over you must get a oil cooler or risk premature wear.

The engines are designed to cool 50ccs, 88 and 95cc's is pushing it.. I would never run 108+ without a oil cooler

I don't really know the differences in clutches, but the trail bikes clutch has been holding up great for me for the last 6 months with a stage 3 88 kit, and I ride the thing daily 2-4 hours a day..

Btw, what are your goals for the bike? Are you looking for somthing to race around on? Are you looking to stunt and do wheelies? Are you wanting to race or jump?

And what other upgrades do you have to the bike? Already have stiffer springs?

My crf50 with a stage 3 88 kit with race head and 20mm carb, will do 50mph on the street with my 4 speed tranny (around 45mph without the tranny) and will almost beat my stock crf150f..

But since its such a small bike with the power of the 150, its very twitchy and very wild. Its pretty friggin crazy in the grass at 50mph

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Thanks for the replies guys - I was under the impression that the TB 50cc race head isn't that much more aggressive than the stock CRF70 head which is supposed to have bigger valves than the 50 - but not as big as the TB race head...

Anyone?

MP

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Kurlon thanks for the reply - I know you have one of these (by the way your bike looks nice man!).

I'm just trying to figure out how to get an economical 117cc kit, with auto clutch that is semi-reliable.

I'm hitting the little private pitbike track for a few laps on it - and then riding a bigger bike. So it's only going a couple/few laps at a time. Maybe a cooler is the hot ticket just for safety reasons...

I'm just curious if the stock CRF/XR70 head will give me enough performance to run with the 117cc kit. I see what you're saying about the older style piston kits too Kurlon - I remember them doing an update of some sort a while back... I'll let him know I want to run it with a stocker head.

Gotta run...

Mike

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Yeah, let Mike know it's a 70 head, and as long as he has the right piston, you'll be fine.

I actually don't have any TB kit in my machine, it's a screwball concoction built to meet class restrictions for a motard series that imploded locally. 51mm bore, 54mm stroke. Makes for a torquey 110cc motor. : )

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Thanks for the replies guys - I was under the impression that the TB 50cc race head isn't that much more aggressive than the stock CRF70 head which is supposed to have bigger valves than the 50 - but not as big as the TB race head...

Anyone?

MP

I was under the impression the TB race head was a ported crf70 head with a race cam

But im not completly sure

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After speaking with Mike at Trail Bikes I was able to get some info - super nice guy by the way and a pleasure to deal with...

The CRF/XR70 head is a much better design than the CRF/XR50 head and the Stage 5 kit will bolt right on and offer fantastic power.

It doesn't appear you would want to do that with the 50cc head as it might not flow enough. (just me talking in that last statement).

I've yet to find out from Mike whether the CRF/XR70 head should use the stock head race cam or the race head race cam. Possibly the 70cc head flows enough to use the race head race cam -or- possibly it's an entirely different design which mates up the the valves in the TB head and cannot be used at all... I'll find out which it is for FAQ info.

I decided to build two bikes - both XR70s. Both 117cc. Both the same kits - and then later one bike will receive the updated head race head and a different carb. We will also be putting an oil cooler on one bike and will measure the diff in heat between the two - back in the day we were unable to discern much heat diff when using an oil cooler on bikes and ATV's - and there is a test out here on the net somewhere with an ATV where they only saw a few degree diff in temps - that didn't surprise me. Out little "trick" which we'll be doing in the future might help to cure that issue.

This should be fun. I'm going to document the outcome step by step as far as the outcome. One bike will have a BBR pipe and one a Big Gun.

Mike

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