-
Enjoy XS650.com? Consider making a donation to help support the site.
XS650.com receives a small share of sales from some links on this page, but direct donations have a much greater impact on keeping this site going.
Stumbly Bumbly
- Thread starter ninskrillz
- Start date
Two PU's
Thank you Sir
Then we are at the problem in finding the Ignition Mark
The re phasing is a job that as all other human endeavors can go wrong and
the rephase has an interval
A rephase on an XS650 is usually at 277º or 270º
There is also the possibility the crank twists by the forces unless welded
Assuming there is a timing mark on the added rotor and it is spot on
How ensure that the other cylinder fires at the correct time ( twisted no more 277 Crank )
Thinking out loud is there adjustment possibility on the pickups 277 or 270 crank or in between
That is also something someone need a boot in the behind for
price $ 899.99 whats wrong with $ 900 plain and simple
I also am glad I am not into modifications Keeping it stock
Maybe a video of top end knocking Blipping could help --- left and right side it would have helped on a stock bike
But worth a try.. perhaps
Aw come on, Gary, you don't need to mess with those VM34s on Madness, you need to hang those fine flat slide pumpers! I doubt they'll need any tuning changes at all, but if they do you'll find that they're the easiest carbs you've ever worked with. The biggest part of the job would be making the push-pull cables, and even that is pretty easy if you start with a pair of Honda cables (can't recall which I used, CX500 maybe?) and shorten them a tad.
The only way to tell would be to get a degree wheel and put dial indicators on the pistons/rockers and put an o-scope on the pickups.
ninskrillz
XS650 Addict
- Messages
- 271
- Reaction score
- 67
- Points
- 28
After testing the ignition components in accordance to Powerdynamo’s knowledge base - I’ve found one irregularity. The ignition coils tested at 10.7 kohms where they should be testing at 6.3 kohms. Everything else tested correctly. I’ll give them a call and verify if my coils are the potential cause of the issue.
ninskrillz
XS650 Addict
- Messages
- 271
- Reaction score
- 67
- Points
- 28
Welp - I got a message back from a US supplier and they were no help. Still haven’t gotten word back from Vape.
I tinkered around with the bike a bit today to no avail. Although I did notice something. It seems the left pipe was getting way hotter than the right. I don’t know if it’s by design of the pipes or not, as the left pipe has a much sharper contour than the right.
I again sprayed the exhaust, this time with starting fluid, to make sure there was no leaking and there wasn’t evidence of an exhaust leak. Did also notice the right side exhaust gasses are coming out with a stronger force than the left at idle. I don’t know if this is indicative of anything or not.
I tinkered around with the bike a bit today to no avail. Although I did notice something. It seems the left pipe was getting way hotter than the right. I don’t know if it’s by design of the pipes or not, as the left pipe has a much sharper contour than the right.
I again sprayed the exhaust, this time with starting fluid, to make sure there was no leaking and there wasn’t evidence of an exhaust leak. Did also notice the right side exhaust gasses are coming out with a stronger force than the left at idle. I don’t know if this is indicative of anything or not.
Can we see some pics of the bike?
Carbs balanced, sync'd?
Have you checked compressions, or done a leak down test?
Carbs balanced, sync'd?
Have you checked compressions, or done a leak down test?
ninskrillz
XS650 Addict
- Messages
- 271
- Reaction score
- 67
- Points
- 28
The bike has vm34s. I’ve synced the cables and idle, and synched the air adjustment screw, although the left carb seemed to want the air screw a bit leaner. I think it was about 3/4-1 full turn different. I have done a compression test and the left was 150 and right was 148. I haven’t done a leak down test.
Here’s the only picture I have currently. Have some cosmetic things to do yet so haven’t had a proper photo shoot!
Any baffles?
Yeah an XS650 motor is going to be sending some mix straight through to the exhaust with straight pipes.
They like some muffler to give a reverse pressure wave to "stuff" the mix in the cylinder.
Yeah an XS650 motor is going to be sending some mix straight through to the exhaust with straight pipes.
They like some muffler to give a reverse pressure wave to "stuff" the mix in the cylinder.
ninskrillz
XS650 Addict
- Messages
- 271
- Reaction score
- 67
- Points
- 28
No baffles - thought about some mufflers or maybe some lollipop baffles.
While no baffles are not ideal, their absence will not account for what your experiencing. I think ignition and or fuel are the cause of your problems. Have you checked your slide diaphragms for leaks? Are you 100% sure your fuel tank isn't vac locking?
Can't really tell from that photo, is the engine sitting level front to back?
If it's tipped back keep in mind the dip stick is at the very back of the motor.
and full "back there" may leave the oil level low at the sump filter.
Can you use the dip stick?
Might try a heat shield tween the pipe and the RH float bowl.
VM34s on it now?
So I reread your first post and think you may want to do a bit of surgery, check what brass is in those carbs, especially the slides, needles, needle jets. Have you tried raising/lowering the needles? 3-4000 is going to be mainly on the needles. Get above that and the mains start doing the job. "Nursing through" usually points towards lean. What air filters are you running?
mebbie a pic as it's currently set up.
Some baseline tuning/brass ideas for VM34s
https://www.xs650.com/threads/help-me-id-these-and-can-they-be-tuned-mikunis.6570/page-4#post-547589
Without knowing the history of the carbs they may contain brass/slides that are only a distant relation to what will make an XS650 motor happy.
Straight pipes will always be a compromise for motor tuning.
If it's tipped back keep in mind the dip stick is at the very back of the motor.
and full "back there" may leave the oil level low at the sump filter.
Can you use the dip stick?
Might try a heat shield tween the pipe and the RH float bowl.
VM34s on it now?
So I reread your first post and think you may want to do a bit of surgery, check what brass is in those carbs, especially the slides, needles, needle jets. Have you tried raising/lowering the needles? 3-4000 is going to be mainly on the needles. Get above that and the mains start doing the job. "Nursing through" usually points towards lean. What air filters are you running?
mebbie a pic as it's currently set up.
Some baseline tuning/brass ideas for VM34s
https://www.xs650.com/threads/help-me-id-these-and-can-they-be-tuned-mikunis.6570/page-4#post-547589
Without knowing the history of the carbs they may contain brass/slides that are only a distant relation to what will make an XS650 motor happy.
Straight pipes will always be a compromise for motor tuning.
ninskrillz
XS650 Addict
- Messages
- 271
- Reaction score
- 67
- Points
- 28
VM34s on it me so no more diaphragms. I did check them BS diaphragms before I swapped carbs and they were in good shape.
Ive ridden the thing around the block with the gas cap off and that didn’t have any effect, that was my first guess. I’ve also verified I’m getting good flow from the petcock.
The engine is basically level maybe a slight forward tilt (completely custom frame), but nothing that I would deem performance hindering.
Ive checked that float bowl at full operating temp and it was barely warm so I don’t think that’s an issue.
As far as brass goes, I’ve got 2.0 slides and 6f9 needles, and haven’t checked needle jets yet. Ive raised the needle to the second from top and that made things much worse and lowered the needle to second from bottom and that had no effect.
What pilot jets?
Valves set somewhere around .006 and .003"?
It's a PITA but checking the valve timing on a rephase might be enlightening.
It's a PITA but checking the valve timing on a rephase might be enlightening.
I am still at leaving the carburetors as is
2 sets have been tried
And there is an out of spec value on the Coil
Vape should be able to respond ..
That is a big difference in some cases Paycheck 70 % up I cannot say it is making a difference here but it is something to work on
10.7 kohms where they should be testing at 6.3 kohms
2 sets have been tried
And there is an out of spec value on the Coil
Vape should be able to respond ..
That is a big difference in some cases Paycheck 70 % up I cannot say it is making a difference here but it is something to work on
10.7 kohms where they should be testing at 6.3 kohms
ninskrillz
XS650 Addict
- Messages
- 271
- Reaction score
- 67
- Points
- 28
currently 27.5 pilot 185 main which for the 2.0 slides is really rich according to griz.
Yeah they’re at .006 and .003.
How do you verify valve timing?
ninskrillz
XS650 Addict
- Messages
- 271
- Reaction score
- 67
- Points
- 28
just got an email from them on the proper way to test the coil. I’ll check again and go from there.
Hi ninskrillz,
never mind it don't run nice! Unless you revise the front forks and add a front brake you'll be too dead to care, eh?
