Timing issue

Message

MX Quad Dad · #71 Post by **MX Quad Dad** » Wed Mar 04, 2009 4:32 am

I'm not sure how the decomp. affects out of time cams. I have seen some weird numbers with cams out of time.

I would say you should be close to max compression after 2 (or 3 at the most) compression strokes. for some reason I get the feeling you are cranking a lot more than that and after going back and rereading I don't know why I got that feeling

I may be wrong but, I have never worked on a ffour stroke motor that didn't have valve overlap. So if you bring the piston to the top of the exhaust stroke, you should see the overlap taking place. this is not a way to time a cam but if is way off you will notice it here.

cannondale27 · #72 Post by **cannondale27** » Wed Mar 04, 2009 1:05 pm

QUOTE (quadsourcemark @ Mar 3 2009, 08:26 PM) <{POST_SNAPBACK}>

Well when I lock the decomp open I get over 180 psi. But its hard on the starter so I stop at 180. One of my kids jacked my camera so no pics tonight. I'm sure the timming is fine. It has to be the decomp spring. When its connected 30psi comp. When I unhook it 90psi comp. I lock the decomp lever open 180 psi plus. Maybe its on wrong. It seems to go on one way.

Mark

That tells me that the decomp is engaging your bucket too much.Reason it is more with spring disconnected is because its not fully engaging.

Take two measurements for me.Valve clearance and the clearance between decomp pin in open position and the bucket.

I would bet you got a redone cam which base circle was cut down.

quadsourcemark · #73 Post by **quadsourcemark** » Wed Mar 04, 2009 6:35 pm

QUOTE (cannondale27 @ Mar 4 2009, 01:05 PM) <{POST_SNAPBACK}>

That tells me that the decomp is engaging your bucket too much.Reason it is more with spring disconnected is because its not fully engaging.

Take two measurements for me.Valve clearance and the clearance between decomp pin in open position and the bucket.

I would bet you got a redone cam which base circle was cut down.

Well I'm sure i'm not over cranking it to get to 180psi. It gets there with-in 3 compression stokes. I'll check the measurements when I get home.

Thanks,
Mark

quadsourcemark · #74 Post by **quadsourcemark** » Thu Mar 05, 2009 2:09 am

QUOTE (cannondale27 @ Mar 4 2009, 01:05 PM) <{POST_SNAPBACK}>

That tells me that the decomp is engaging your bucket too much.Reason it is more with spring disconnected is because its not fully engaging.

Take two measurements for me.Valve clearance and the clearance between decomp pin in open position and the bucket.

I would bet you got a redone cam which base circle was cut down.

The new cam is the intake not the exhaust. The exhaust cam is the same one I used before with no issues. The only change on the exhaust cam is the counter weight. It seems like it's to light.

Mark

cannondale27 · #75 Post by **cannondale27** » Thu Mar 05, 2009 12:31 pm

The wieght of it has nothing to do with cranking compression.As long as the spring holds it closed while cranking its doing its job.Once it fires as long as its free it will disengage.Ton of force there.Just take the measurements.

quadsourcemark · #76 Post by **quadsourcemark** » Thu Mar 05, 2009 5:43 pm

QUOTE (cannondale27 @ Mar 5 2009, 12:31 PM) <{POST_SNAPBACK}>

The wieght of it has nothing to do with cranking compression.As long as the spring holds it closed while cranking its doing its job.Once it fires as long as its free it will disengage.Ton of force there.Just take the measurements.

I think found the problem. The decomp pin that strikes the bucket is binding. It has a lot of play...in/out, up/down. The spring also is damaged. I'm going to replace the whole decomp assy. I should have done that in the begining but I tried getting off cheap replacing the weight. Does anyone have one to sell? I know Brad @blackwidow has new ones in stock but he's hard to get a hold of these days.

Thanks,
Mark

peterock · #77 Post by **peterock** » Thu Mar 05, 2009 6:12 pm

http://www.cannondaleriders.com/forums/ind...showtopic=19694

Canniboomer · #78 Post by **Canniboomer** » Thu Mar 05, 2009 7:45 pm

I have some updated drop-in cams available, with drivegear @ stock alignment, new bearing, seal and the small decomp parts as needed. Pricing would depend on your core swap and the components of each,.... like if the backing plate and weight arm(s) of each are billet or powdered metal. If interested in that option or misc parts, just email your cam description.

quadsourcemark · #79 Post by **quadsourcemark** » Thu Mar 05, 2009 11:44 pm

QUOTE (Canniboomer @ Mar 5 2009, 07:45 PM) <{POST_SNAPBACK}>

I have some updated drop-in cams available, with drivegear @ stock alignment, new bearing, seal and the small decomp parts as needed. Pricing would depend on your core swap and the components of each,.... like if the backing plate and weight arm(s) of each are billet or powdered metal. If interested in that option or misc parts, just email your cam description.

Thanks guys but I did got a hold of Brad and he's got one on the way. I'll post the results when I bench test the engine again.

Thanks,
Mark

cannondale27 · #80 Post by **cannondale27** » Fri Mar 06, 2009 1:08 am

QUOTE (quadsourcemark @ Mar 5 2009, 11:43 AM) <{POST_SNAPBACK}>

I think found the problem. The decomp pin that strikes the bucket is binding. It has a lot of play...in/out, up/down. The spring also is damaged. I'm going to replace the whole decomp assy. I should have done that in the begining but I tried getting off cheap replacing the weight. Does anyone have one to sell? I know Brad @blackwidow has new ones in stock but he's hard to get a hold of these days.

Thanks,
Mark

Okay this is going to come off bad but its really obvious you have no clue what is going on.I tried to help and you wont even answer some simple questions such as valve clearance and decomp clearance.Please get someone to look at your motor or send it out.Otherwise you are just wasting all our time and your $.Sorry for being blunt but you will thank me later.