Yfm350 serious power build!!

[yfmdeuce]

I got a question that fits right in on the topic. I race timed events that that 16 sec to 25 sec a run. My class it the 0 to 400 class, so i race alot of 400ex and z400. They usually out run me because of the long run into the arena and back out. So really what im trying to say is they out run me in the 50 yard drag race. I have the JE 366 kit and hot cam stage 1 with open air box. What do i need to do to keep up with them short of a stroker kit or something crazy. I was thinking about going to a more agressave cam and +1mm intake valve and hd springs. Maybe shave the head a little to up comp and shave a little weight off of the fly wheel to help it rev faster. The cams i have look at have different grinds and i have no idea what would work best. Like i was saying our events mainly consist of 50 -60 yard sprint, turn around barrel or pole, then another barrel or pole, then a 50 -60 yard sprint to the finish. (thought it may help to know what riding style was). any advise would be great

 

['00 WO-YA!]

I forgot to mention that Greg from CWR told me that JE builds his custom pistons so I guess they could build the piston in a .040 or .060 over instead of jus stock or .080, you just may have to order through a company that uses them alot.

 

[beastlywarrior228]

I got a question that fits right in on the topic. I race timed events that that 16 sec to 25 sec a run. My class it the 0 to 400 class, so i race alot of 400ex and z400. They usually out run me because of the long run into the arena and back out. So really what im trying to say is they out run me in the 50 yard drag race. I have the JE 366 kit and hot cam stage 1 with open air box. What do i need to do to keep up with them short of a stroker kit or something crazy. I was thinking about going to a more agressave cam and +1mm intake valve and hd springs. Maybe shave the head a little to up comp and shave a little weight off of the fly wheel to help it rev faster. The cams i have look at have different grinds and i have no idea what would work best. Like i was saying our events mainly consist of 50 -60 yard sprint, turn around barrel or pole, then another barrel or pole, then a 50 -60 yard sprint to the finish. (thought it may help to know what riding style was). any advise would be great

yes do that and .430 grind

I forgot to mention that Greg from CWR told me that JE builds his custom pistons so I guess they could build the piston in a .040 or .060 over instead of jus stock or .080, you just may have to order through a company that uses them alot.

huh wonder if he can do a higher compression

 

[1998yamahawarrior]

[ this thread has tons of motor mod info can it be a sticky? just thinkin aloud here ]

ok im going to try and measure the oem head volume this week with dans head and see what i get

Might make it a sticky, but it will get moved to tutorials then.

 

['00 WO-YA!]

Hey Deuce, tell some of these cats what your tire size & gearing are & that'll help too. Anyway, I have a feeling that you're gonna hear get a decent professional port job, a good cam, prolly like a Web .430, something more rev happy(not bashing the hotcam but everyone says there are much better grinds) & a carb to support. Basically you're in a drag race so you're gonna want to gear for short distance runs, stuff like that.

 

['00 WO-YA!]

yes do that and .430 grind


huh wonder if he can do a higher compression

Haha, we musta been posting at the same time! As far as the piston goes I'm sure he could get it but at a cost. You know how that is, anything that strays a lil from normal is gonna cost b/c of fewer production pieces. Prolly if a group of 50 people or more all wanted Greg to order something specific it would be easier but don't quote me on that.

 

[yfmdeuce]

Hey Deuce, tell some of these cats what your tire size & gearing are & that'll help too. Anyway, I have a feeling that you're gonna hear get a decent professional port job, a good cam, prolly like a Web .430, something more rev happy(not bashing the hotcam but everyone says there are much better grinds) & a carb to support. Basically you're in a drag race so you're gonna want to gear for short distance runs, stuff like that.

I run 18in turftamers with 15/40 gears. I agree on the hotcam, at the time i built the motor i didnt want to get into the putting in hd springs and such. Thats a huge sign of how mild the hot cams are on the grind. LOL. Yea, its basically a drag race situation with a lot of sharp turns and against the clock, not heads up.

 

[duneracerweston]

In those straits do you wind out the gear and shift? Or is it just long enough to windout one gear?

 

[yfmdeuce]

In those straits do you wind out the gear and shift? Or is it just long enough to windout one gear?

depends on the set up. some times go from 1st to 2nd and max out at line and others have to catch 3rd. But mainly 2nd-3rd and down to 1st to do the 180 turns

 

[beastlywarrior228]

eh id stay with that gearing a good cam and head massaging will really wake it up

 

[yfmdeuce]

eh id stay with that gearing a good cam and head massaging will really wake it up

I've heard the web .430 a couple a times so that seems to be the fav. Guessing that is a top end cam. can someone with it give a little feed back on how it worked for them.

 

[beastlywarrior228]

it a mid to top, unlike the .450 which is all top. just make sure you dont get a "race" grind, the duration is too long

 

[yfmdeuce]

it a mid to top, unlike the .450 which is all top. just make sure you dont get a "race" grind, the duration is too long

i was just checking out there site. say clearance have to be checked on the .450 and head milling may have to be done. WOW. Thinks. think i will be going with the .430, the hotcam made a big difference and it is almost stock. I would say a .430 would be a huge diff.

 

[duneracerweston]

Yep good gearing and that's a good cam oversized intake valve and port it and it will do good but oversize carb would make it even better!

 

[Hdale85]

If you are getting high up in the revs might help to upgrade your valve springs and what not. But if you're not maxing out in revs then it probably isn't a problem.

 

[beastlywarrior228]

no if your gonna go with a cam with that lift and duration you need the springs, its not an optional thing

 

['00 WO-YA!]

Do the springs. If you're gonna have the head off for port & polish replacing the springs is simple.....if ya have the tool. I went ahead & bought one b/c I figured I'd make my junk part of the family & I'd need tools to work on it. Even if I weren't doing portwork on the head I'd still take the time to remove the head & replace the springs, what's a few hours. It would also be a good time to inspect & replace the timing chain & guides if necessary. Hey, while we're on the subject, would someone like to suggest a good chain & guides? Would Yamaha be the best replacement of are there better options? I've seen some stuff on ebay but idk how reputable the manufacturers of some stuff are.

 

[Hdale85]

Yeah since there are only 2 it's not that terribly expensive But titanium springs will help prevent valve float.

 

[duneracerweston]

There's a lot more then 2 out there did timing chain and oem guids and you should. Be good

 

['00 WO-YA!]

There's a lot more then 2 out there did timing chain and oem guids and you should. Be good

So just OEM stuff from Yamaha is what you'd recommend? I just didn't know if there were a chain that's less prone to stretch but I figure that heat plays a major role in that. I'm also pretty confident that most engines have more wear on the guides that people think too...causing even more slack in the system as it wears.