[itschris]

I got a buddy with a Raptor 700, who is looking to stroke it 5mm's. What rod length, and pistons does he need? Also, does the combustion chamber need to be machined 2.5mm to fit the new crank? I'm guessing it does, to clear the piston and to get the squish right. But, he thinks the hotrods +5 crank is a direct drop-in, with no modifications. Any Rappy guys out there that could help me out? Thanks.

 

[itschris]

Ok, so the HotRods +5 crank is a direct bolt-in and go. It says on their site that you use the stock piston. I'm guessing the rod is 2.5mm shorter than stock, to keep the squish right. I would think that having a longer stroke with a shorter rod would put WAY too mush side load on the piston skirts. Sounds like bad news to me. What do you guys think?

http://www.hotrodsproducts.com/index.cfm?f...p;productid=555

 

[T-Rex]

The shorter rod will put more stress on the piston skirt. In my opinion no, stroke it and get a piston with a wrist pin located higher in the piston closer to the crown. JMO..

 

[Radar]

If it were me I'd use a kenz cycle setup and whatever they recommend for piston rod etc. I've seen some real fast 730 and 760 non stroked rappys done by kenz. I know of a 730 that runs mid/high 4's. Its a mover.I'd do bore before stroke first. You didn't say what other mods it has.

 

[average_joe]

depending what the stock stroke and rod length are, adding a alittle more stroke and decreasing the rod length slightly might not have a detrimental affect on rod angle..........it pretty much depends on what the rod ratio is for a stock raptor. im not familiar with the raptor so i cant say what the stroke or rod length is. just trying to help

 

[itschris]

T-Rex, that's what I told him.

From what I've gathered, stock stroke is 84mm, and the rod length is 108mm, which almost seems kinda tight to me in the first place. The HotRods crank he is looking to buy is 89mm stroke, and I'm guessing it has 105.5mm rods. The only reason I think that, is because it uses the stock pistons, and the only way to get the squish right, is to shorten the rod length 2.5mm's.

 

[average_joe]

well i hope wiseco would have done some testing so their setup doesnt cause excessive wear on the motor. sorry i couldnt be more help, im not really that knowledgable with 4strokes.

 

[camatv]

how long is the rod on a 450??

i know of 2 hot rod equiped rappys stock bore, easy install, ( besides all the motor dissasembly and stuff) no crazy cutting here or case mod there it just drops in the cases are a lil more work than you might think get a book and throughly look at what all it takes to install these corectelly. gaskets, tq values, assembly lube, crankremoval, install tools. the motors are pretty particular on keeping things corect. the rappys i know of are holding up well and have been spraying NOS on top of the crank.

if you go bigger bore you will most likely have some issue's with head gaskets or just ARP stud it and get the head o-ringed right off the bat. the stock bore and stock style head gasket are very nice design's there may be some advances with that issue but i am not sure what.. if it was me i'd look into the kenz big cam's and porting and bigger valves, leave it stock bore and spray the do do out of it.. 100+hp on nos is easy to get.. with a relatively small shot. 35-40 shot of nos. OR a really big cc motor 800+ with a larger crank

60-70 reliable hp is very easy to get with the lil stroker

 

[Radar]

And they are fast even with only 70hp.they make gobs of torque and can turn huge paddles.

 

[bigbadc210]

my views on boring the cylinder and spraying is the thicker the better, we have a 727(stroker crank) stock bore and it runs pretty salty. the raptor motor is a fairly complicated peice of work but the strked crank really woke it up nicely.

 

[QUIKSHRK]

a couple of my friends have some RE ported 727's with hot rods 5mil's. they make 72/55 and they havent had an ounce of trouble out of them.

 

[RagunCajun]

threads like this make me want to sell my dirtbike to fund a 700 build. 70hp is insane! Is that on race fuel or alky or what?

 

[Raptor Trent]

I run the 8 mil kenz stroker crank. It is a drop in crank with no modifications. I do run a stroker piston. I would call ken and talk to him about it before any big decisions are made. Ken is very knowlegable and will talk to you if you call him. The phone call is alot cheaper than the outcome of putting in a faulty part. jmo

 

[dragrap379]

i know this is off the subject,but is +8 crank & +2 piston a good combo for the 660? i'm thinking better head gasket surface with more tq from the crank.