Has anybody contacted Bill at B&B and asked him about valve clearance?
He might have specs on his 351 kit that are different from the Kawi ones.

 

more looking at the chart here Camshafts

Stock exhaust closes (@ .050) 5* BTDC Both 101 and 293 close at 8* and 7* ATDC So adding 10.5 retard gets us closer to the webcams.

Stock Intake opens (@ .050) at 2.5*ATDC. Webcams Opens 101 and 293 at 10* and 9* BTDC, so adding 10.5 advance again gets us closer to webcams.

food for thought. It took me a while just to write that one.

I am a mechanic, Not a motorhead.

David

 

From the camshaft graph you sent, I believe the exhaust is open at .125" and closing and the intake is at .13" and opening when at TDC with the cam rotation of 10.5 degrees.
That is more than the 293 grind that is shown.
I am talking about the overlap cycle, not compression.

Edit: my mistake. I doubled the degree from 10.5 to 21 by mistake
Disregard the calculation above
The lift a TDC is much less than I thought.

 

Hey Marcelino,

I was going to ask this yesterday but forgot.

In your original post you had a sprocket tooth count of 34 for your KLX250EFI.

While I had mine out I did a count and found it has 32 teeth. That's also what the diagram in the service manual shows. I double and triple counted just to be sure. According to the Ron Ayers site, the p/n is 92046 (from memory).

There will be a (very) small difference in degrees between the two. 720/34/2 = 10.58 and 720/32/2 = 11.25.

I'm currently running the mod on my 250 without any difficulties and plan to keep it.

Could this difference perhaps be just enough to affect the 351, perhaps?

 

Itīs actually 12046-0001.

SPROCKET,CAMSHAFT,32T - Search : 12046-0001

 

I'm awaiting to hear someones results that has done the mod with the 351, I think David was right? I had 100 miles on the fresh cam mod / 351 combination before this all happened. Guess we'll see what happens.

 

At least I got the "...46" part right, anyway. I mentioned I was going from memory but I didn't think it's gotten that bad!

Over what hill? I don't remember going over any hills!

 

Yes , I counted badly , I counted 17 teeth above the cylinder headīs edge looking at some photos so I assumed 34 in total . The day I did my cams was the first time Iīve open the cover on my KLX and it didnīt pass trough my head to count the total number of teeth a sprocket has ( in this case itīs of no consequence if itīs 32 or 34 ) This changes the advance and delay for the intake and respectively the exhaust cams with 0.7 degrees at the cranckshaft and 0.35 degrees at the cam .
It does not change anything .

 

Nah, itīs fine with me. Just thought Iīd give you a little help.

I also saw 32T over bikebandit.com, and I count 32 on the picture Marcelino posted.



Still doing the mod, thou.

 

Been so busy working & fishing I have barely been able to keep up with this thread!

Thanks Marcelino I will probably be doing this mod next time I have to get into the top end(Hopefully valve clearences) Ill do it on both bikes my 351s for the perfomance and the GFs 250sf for noise abatement.

I was thinking while reading this that we should put our heads together and come up with a way of marking the cam sprockets that this mod has been done. I just envsion someone buying a used KLX 250 without knowing it had this mod, installing a BB351 and timeing the cams by the book thereby puting the cams out by 2 teeth or 42degrees(assuming I understand the mod correctly) This could also occur if one of us does the mod but then later takes it to a shop for something.

I know one should turn the bike over by hand after reinstalling cams but I am just saying there is some serious potential for inadvertant harm. & Yes if you know about the mod you could remember to look at which holes the bolts are in, but for the uninformed...........

I have a killer engraver and will be engraving something on the sprockets.

Cheers & thanks again Marcelino