Ti valve / seat problems and questions from a non 250r guy.

Greetings 250F riders,

Im normally in the CRF 450 forum.

 

but i have another bike more similar to yours than my 450

its an Aprillia sxv550,its a twin the cylinder heads are a spitting image of the CRF250 heas except the intake port is more straight down.

the crf250 valves reportedly fit this head.

Anyways I have valve issues, and the aprilia website/forum is full of wankers talking about blinged out bikes and other useless banter so I figured Id check in with some people who i know are intelligent, HONDA riders.  And the ones with the same issue I'm having happen to be you 250f fellows.

 

so hers my questions,

whats the most economical method of addressing the valve issues?

does one really need to replace the seats with beryllium copper and buy the super trick chromium nitrided valves? (I have twice as many to deal with)

or do the copper seats and oem valves suffice?

or would i be better off with oem seats and chromium nitrided valves?

 

also is it visually possible to identify valve seat material?

when I cleaned my head the seats appear to be a copper color.

 

it seems like you guys were having intake valve problems,

my intake valves seal and my exhaust valves are the problem

 

im almost wonderinf if an oem crf250 valve may be better than what im currently using.

The "standard" way that CRF people increase valve life is by putting kibble white stainless valves (and springs) in.

 

The springs must be changed to special springs for stainless valves.

 

It's hard to really get any concrete reliability data, but it seems like the stainless valves last 2-3x longer than the titanium valves which honda uses.

 

The biggest killer of valves is high RPM. Top racers would be ecstatic to get 100 hours out of a set of valves. Trail guys can often push them a lot longer, maybe 4-5 years of every other weekend riding.

Mudguy is correct.  SS valves and use the required heavy spring kit is the way to go.

I don't know that the 250 valves are a direct swap but we can make you some valves that are stainless the only other issue would be a heavier valve spring to control those valves. We have tons of springs Im sure we can come up with a winning combo. If you are interested you can email me at Jeff@aperaceparts.com, or give me a call @ 661-256-7309

Nothing wrong with the Aprilia vavles, some have 1000's of miles out of them with no issues. The XV engine is a reliable engine if put together right. Some of the engine had bad retainer and buckets but not valves. The problem I see is carbon build up which isn't a valve fault, tuning problem. Who are all the people having vavle problems?

the biggest issue with the crf heads is the valve seat material. not the valve itself.

unfortunately I do not think stainless steel valves are a viable option for me, its a super moto bike the rev limiter is 12500rpm and I spend alot of time at 12000, and i never drop it below 8000.

 

and she sees alot of miles in the canyon, i live at the base of "the twistiest road in california"

 

the Aprilia parts supply I deal with said that the crf250 valves will fit but im not sure what year.

 

theres surely carbon build up on the valves but not on the seat, and the clean ring on the valve, the valve appears to be pitted. while the seats are perfect.

 

It came to my attention they are not sealing when i was measuring the chamber volume for a set of pistons im having made and water was running out of the exhaust port :cry: 

its not a valve clearance issue the camshaft was not in the head at the time.

 

I know peope will say ba ba ba its a race bike the valves can only survive so many hours.

it never sees dirt, i dont understand how the sport bikes titanium valves can survive years and years and years of 15,000rpm action.

 

what im considering is,

A Ron Hamp valve job,

or a Ron Hamp installation of copper berylium seats and stock valves

or a Ron hamp installation of copper berylium seats and Del West valves $$$$$$

Nothing wrong with the Aprilia vavles, some have 1000's of miles out of them with no issues. The XV engine is a reliable engine if put together right. Some of the engine had bad retainer and buckets but not valves. The problem I see is carbon build up which isn't a valve fault, tuning problem. Who are all the people having vavle problems?

well,

i guess they can be reliable,

but there is an inherent design flaw which most people lack the capacity to understand or they just dismiss it,

the liners grow about 0.004" when they reach temperature and fatigue the head gasket which is used to hold them down over time.  so the head gasket has a finite life

 

a better approach is to eliminate the gasket using wills rings or cooper rings and put the liner in direct contact with the head.

 

mine blew not only one, but both head gaskets,  it was last assembled by the premier west coast aprilia mechanic well known ont he aprilia boards so it would have been assembled the way most aprilia folks would consider correct.

unfortunately I do not think stainless steel valves are a viable option for me, its a super moto bike the rev limiter is 12500rpm and I spend alot of time at 12000, and i never drop it below 8000.

and she sees alot of miles in the canyon, i live at the base of "the twistiest road in california"

the Aprilia parts supply I deal with said that the crf250 valves will fit but im not sure what year.

theres surely carbon build up on the valves but not on the seat, and the clean ring on the valve, the valve appears to be pitted. while the seats are perfect.

It came to my attention they are not sealing when i was measuring the chamber volume for a set of pistons im having made and water was running out of the exhaust port :cry:

its not a valve clearance issue the camshaft was not in the head at the time.

I know peope will say ba ba ba its a race bike the valves can only survive so many hours.

it never sees dirt, i dont understand how the sport bikes titanium valves can survive years and years and years of 15,000rpm action.

what im considering is,

A Ron Hamp valve job,

or a Ron Hamp installation of copper berylium seats and stock valves

or a Ron hamp installation of copper berylium seats and Del West valves $$$$$$

Nobody has an recommendation on this?

Sounds like a plan but if there's a sodium-filled exhaust valve available you might wanna use them. Go with the best you can afford and run the clearances as tight as you comfortably can.

Edited by Eddie8v

Do they have sodium filled exhaust valves for crf250s? Because other than stock I have to use crf250 valves. They fit in this unicam clone.

I doubt it, but I am sure you could get some made...

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