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Change jetting for more aggressive cam?


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Ok to start out, I have a TRX/XR400 motor with a 458 stroker kit (87mm piston and a +7mm stroke). I currently have an XR400 genuine Honda HRC cam in it. I would like to switch to a slightly more aggressive Hotcam Stage 3 "stroker cam".

Here are the specs for the two cams

HRC cam:

Intake lift - .350

Exhaust lift - .339

Intake duration - 254

Exhaust duration - 256

Hotcams Stage 3 stroker cam:

Intake lift - .358

Exhaust lift - .354

Intake duration - 262

Exhaust duration - 257

So with .008" more lift on the intake and .015" on the exhaust, coupled with a little more duration would I need to jet it a tad richer than before? I'm running an aftermarket (Sudco type) Keihin FCR 39.

Thanks for your help!

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Damn, 7mm stroker, didnt know that was an option. I believe if you have your jetting dialed in with out the cam, then you shouldn't have to change it.

I just installed a 440 kit with the stage 3 cam.

I'm curious who did the stroker, the only ones I have seen are 4mm.

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How do you like the stage 3 cam?

I was also wondering about the piston to valve clearance going to a higher lift cam. Surely I should be ok going to the stage 3 cam right? I mean its only .008" and .015" more lift than the HRC cam. Anything to worry about or am I thinking too hard about it? Nothing has been decked, stock gaskets, etc. Hotcams website scared me when they say the stage 3 is for use with the Hotrods 440 stroker kit only. But I see many others running it without that kit.

And this is a GT Thunder stroker kit. The crank is stroked 7mm out over stock and it utilizes a custom short skirt 87mm (416 bore) JE piston with a relocated wrist pin hole. It's a runner for sure, mad torque.

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I just buttoned up my engine yesterday. I have to put it back in the frame as well as finish putting the rest of the bike together. I used plastigauge to check it and it didnt touch it, but I dont think I had the head tightened all the way, but I buttoned it up and spun it over with no issues.

Is this engine in a XR or EX? I was wanting to go with a stroked crank, but it was cheaper to go the route I did with a bolt on 440.

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