Yfm350 serious power build!!

['00 WO-YA!]

On the Raptor 700's anyway, the +1 head out performs the +2. This is a very interesting thread, alot of knowledge in here!

I haven't studied the 700 head but I can apply some basic cylinder head knowledge to it. The idea of a larger valve is great, especially if the bowl is blended into the seat properly & the valve angles are correct. However, the problem with a larger valve is that it gets physically closer to the chamber edge, thus shrouding the valve & obstructing the flow. The chamber should be properly radiused in most cases in order to allow the larger....

 

[duneracerweston]

man you really got my gears going on this one i remember thaere was a member on here that took and made his own valves so he could get +2 intake and a +1 exh valve set up i wonder if you did that how it would flow after the proper head work :] that would be a fun ride with a powroll or web .430 cam oh man that would be intinse

 

['00 WO-YA!]

.....larger valve the necessary room to flow properly. In the case of the +2 valves in the 700 head.......mmm, maybe this is why. In the case of the YFM350 head, the canted valve design allows the valve to unshroud itself as it opens b/c it moves further away from the cylinder wall. There might be a lil low lift flow gained by radiusing the chamber around the valve properly but I'm uncertain as to how much. A cylinder head porter that "really knows cylinder heads" would be able to explain this much better than me. I have a trusted friend (professional head porter)in Texas that I would likely have to port one of my Warrior heads when I decide to get super serious about it. His name is Lloyd Elliot & he's badass!! BTW, I love cylinder head theory, lol! It captivates me!

 

[duneracerweston]

well it seems you understand it pritty well thats forsure i think im going to try and contact cv4 and see if they have the valves in pluss 2 that were ment for a diferent bike if not then ive got a buddy that works in a machine shop i might try and have him cut a set of +2 valves and redo the head in dans and see how it turnsout

 

['00 WO-YA!]

Yup, with the right tools & some brains you could cut your own valve from a larger valve, people used to do it in Small Block Fords years & years ago with Small Block Chevy valves. Just about anything can be done man. The only thing to think about is the valve seats get closer together & likely will be more failure prone b/c of that & since those valves are angled towards one another they will intersect at some point, I have no idea at what point this will happen but I know that larger is closer & cams with more lift & duration will have more valve overlap....just think about it. Maybe there's enough room that it would never be a problem, I hope that's the case.

 

[beastlywarrior228]

heres the thing though its probably been tried before and didnt work well which is why you can only get a +1 intake

 

[duneracerweston]

or someone just thought "its a warrior who mods awarrior thatmuch anyways so im not going to mess with it" and maybe it hasnt been tried but i dont see the harm in trying it :]

 

[1998yamahawarrior]

Id say contact some one like FST and see if they have tried or done any testing with the bigger valves like your talking about. With as long as warriors have been around, Ill almost bet its been tried and a reason it isnt being done.

 

['00 WO-YA!]

That's alot of valve in very confined chamber. I could forsee burnt valves b/c of the concentration of heat at where the seats are nearest one another. I'm sure you can get all that ya want from one of these engines with the +1 I&E VALVES & Ports to match.

 

[duneracerweston]

ya probably but thats the thing they dont make a oversized exhaust valve either!!! so im trying to figur out why they wouldnt the exh valve is much smaller then the intake so it would be logical to me to oversize it too

 

[beastlywarrior228]

maybe talk to mickey about it but id be happy with only a +1mm intake

 

[duneracerweston]

not me i want bigger and better i really hate running parts everyone else already has so new and better is always on my mind

 

[beastlywarrior228]

eh thatll take some r&d bigger is not always better, kinda like porting wrong and take too much and itll be a power loss

 

[duneracerweston]

:evilface:^^ then you stroke it more:evilface:

 

[headache]

yeah you can screw up a head by porting it wrong. Also remember that bigger valves and ports also loose intake velocity.

 

['00 WO-YA!]

Port shape is more important than port volume. There seems to be a common misconception among folks about port volume causing a loss of velocity in a port. This has become commonplace amongst folks but the truth is that the volume of a port will be what it will be after the porter is happy with how the cylinder head moves air. Port volume is more of a bi-product of the correct shapes & dimensions inside the runner. This is way too big for me to explain but I just don't want people to "Believe" that port volume is soley resposible for how a cylinder head will perform. There are key areas in the runner that should be shaped & sized properly per the application...for example, an engine operating under 6000rpm will require a port to move air differently that a high end performer. YES, it is possible to make a port to big but not likely with the casting we have "IF" the port is shaped properly. Really, just having a head ported & throwing whatever popular cam at it isn't ideal. It may work ok but not optimal!

 

[elwood]

on that subject, There is a local shop here that told me he can port my head with D shaped intake port and when he is done it will flow test better then a standard ported head with a +1 intake. He told me that he has numbers before against Powroll back when they still did head work. Like I said this is what he told me. And as for cost it would be by the hr and I really didn't want to know the price cause it would be to much.

 

['00 WO-YA!]

on that subject, There is a local shop here that told me he can port my head with D shaped intake port and when he is done it will flow test better then a standard ported head with a +1 intake. He told me that he has numbers before against Powroll back when they still did head work. Like I said this is what he told me. And as for cost it would be by the hr and I really didn't want to know the price cause it would be to much.

My boy Lloyd quoted me $250 but I know it'll be done right!

 

[duneracerweston]

It was 300 to have mine done and he put the cam and valves and springs in at the same time (pluss the cost of parts) so my head parts and all cost 580 and dang dose it flow

 

[YN89]

Sorry to jump inn or sumthing but what are your thoughts on a amr monster coil??