Yfm350 serious power build!!

[rappy'97]

I just had it apart to clean it, and fix an issue, and decided to put the hood on it...
fenders, bolts, air box, bumper, grab bar, rear brakes, exhaust can, piston, cam, headlights, and a bunch of other stuff I cant think of... its light. I can easily pick up the rear, and the front. Which is normally a bit hard to do.

 

['00 WO-YA!]

Unfortunately I don't have this info yes as I yet to have a good spare head to play with......I have jumped back on my CBX bike project because
it cooled off a bit.....
When i know...everyone here will too......

Jebby

It's cool guy, I completely understand. I do have a spare head but I'm not willing to sacrifice it, lol! I wish I could just find a cracked junker to toy with. I do have an old yfm225 head, similar design but smaller scale, I may see what I can tear up on it, lol!

 

[beastlywarrior228]

ive got an empty shell

 

[Jebbysan]

ive got an empty shell

You have a head casting?

 

[beastlywarrior228]

ya an empty one, it came with the 446

 

['00 WO-YA!]

Donation to science?? How much would ya have to have for it man? If you're volunteering to let it go I'll take it if it's reasonable. Maybe Jebby & I can put our heads together & develope something that will work well. Kinda makes me wish that Jebby was closer, you'd be surpised the awesomeness that can be designed over a few beers

 

[87warrior917]

Kinda makes me wish that Jebby was closer, you'd be surpised the awesomeness that can be designed over a few beers

Or a bottle of JD :tup:

 

[beastlywarrior228]

or a jar of shine

ya id let it go

 

[duneracerweston]

So if ya can figure this out I may have a head for you to do it to if you wouldn't mind

 

['00 WO-YA!]

So if ya can figure this out I may have a head for you to do it to if you wouldn't mind

Wouldn't really be a problem for me, I'd like to do whatever I can to try to pick these engines up a bit. I'm putting alot of thought into the relief in the chamber & I can only assume that the placement would be on the edges of the valve seat out towards the cylinder bore. This will definitely add some cc's to drop compression a bit but I don't know if there's much to gain from the unshrouding of the valve since it's angled toward the bore center & unshrouds itself as it opens anyway.

 

[beastlywarrior228]

when you remove cc's you raise compression

 

[Jebbysan]

It wouldn't take much to drop compression to an acceptable level becase there is just not a bunch of swept volume....
The bonus here is the chamber efficiency would increase....the quench would be better...and the resulting lower cylinder pressure and better
squeeze would result in a efficient high compression setup....
I think there is 1-2 horsepower in the chamber alone....
Another 4-5 in porting.....(assuming cam)
1-3 in compression.....
1-2 in bore size....
This would put you square at 30-32 hp....and the engine would be understressed and "happy"....plus my bore stroke would make it a
rev monster....8000+ rpm....
This is all theory....

Jebby

 

[rappy'97]

Is that uncommon to run 8800rpm?

 

[Jebbysan]

Is that uncommon to run 8800rpm?

There is a rev limiter stock.....but no it may not be uncommon....but stock does not make any power there...just noise.....

Jebby

 

[rappy'97]

There is no rev limiter on the 350...

 

['00 WO-YA!]

when you remove cc's you raise compression

I'm sorry guy, I was still sleepy this morn, not thinkin straight. I wasn't translating from mind to finger very well, lol! Yes, removing cc's would raise compression, removing chamber material will raise chamber size & will lower compression. My appologies & I fixed the post.

 

[beastlywarrior228]

ive never really seen much with removing material in the combustion chamber.

man i need to stop listening to you guys, you gonna make me go out buy another motor and do a je 366 with all this head work, .430 cam and flywheel key

 

['00 WO-YA!]

It wouldn't take much to drop compression to an acceptable level becase there is just not a bunch of swept volume....
The bonus here is the chamber efficiency would increase....the quench would be better...and the resulting lower cylinder pressure and better
squeeze would result in a efficient high compression setup....
I think there is 1-2 horsepower in the chamber alone....
Another 4-5 in porting.....(assuming cam)
1-3 in compression.....
1-2 in bore size....
This would put you square at 30-32 hp....and the engine would be understressed and "happy"....plus my bore stroke would make it a
rev monster....8000+ rpm....
This is all theory....

Jebby

Jebby, would you mind describing your theory a lil more in depth? How removing material from the chamber in specific areas will effect the overall efficiency of the chamber, I think that would be a valuble piece of info to this thread. Also, what area are we talking about speciffically, I continue to think outside the valve seat.

 

[beastlywarrior228]

i think trying to go as hemispherical as you can would be best to promote a swirling motion

 

[Hdale85]

ive never really seen much with removing material in the combustion chamber.

man i need to stop listening to you guys, you gonna make me go out buy another motor and do a je 366 with all this head work, .430 cam and flywheel key

I'll just trade you my stock engine with the 366 components for your 446 lol