My bike is not running smooth - advice needed

[Hoople]

My coil is single fire and ignition is Ultima, I do not have cam sensor. It is very simple wiring and it worked correctly more than 1000 km.

So your using a #53-60 ignition module with a #53-632 coil (2-4 ohm primary windings) and an Ultima timing rotor?
If so, taking ohm readings on the coil tells you very little as to it's condition. You must use a dielectric strength test to determine condition.

But first... I understand that the bike will not idle smooth and it will not idle at its target idle speed and will stall-out if idle speed is attempted. But knowing that, how does the engine pull under wide open throttle. Does it pull hard without a miss-fire if placed in 5th gear and pulled at WOT for a stretch. Are the only problems you have at the low RPM region (idle area).

 

[Piotra]

I use exactly #53-644 Ultima programmable ignition module only (its other than #53-60). It is set in single fire, no VOES, and rev limit 5500. The coil is Drag Specialities (2102-0226). On dragspecilaities website in description there is information that this is "COIL SINGLFIRE 2.4 OHM BK", 30,000V output. I tested both primary circuits in this single fire coil and the radings were about 3.5 ohms. I have other coil when I was riding with dual plugs - DC6-4 Twin Fire dual output coil by Dynatek and this has also the same reading at primary circuits. Unfortunetly I couldnt reach any reading while testing secondary circuits on both coils (should I have the power on during testing? because I tested without power). But this Dynatek coil I used only 200 km and than I changed two spark plugs to compression release valves so I'm sure that this is good.
Today I changed the coils. I removed this Drag Specialities and I mounted Dynatek. But the bike didn't want to start without attached all four cables. So I instaled four cables and to two unused I instert spark plugs and I grounded them. Than the bike started. It worked the same on both coils. I couldn't test it on road because I had these to unused plugs on cylinders.

The spark plug wires are Taylor Spiro Pro Cores. Today I changed the wires and I used another pair (but the same type, as I wrote I used dual plug application so I had two usued only 200 km on shelf) and nothing happened. The bike worked the same.

The spark plugs I use are 6R12 (really I'm not sure when I wrote now). I try to change them today for Accel but during idle the bike worked the same on both. Than I changed again to HD spark plugs.

AGAIN SYMPTOMS:
I took the bike for a ride and again I runned only 1-2 km because it's working bad. When I start riding or I'm riding very slowly and gently accelerate the bike is not running smoothly, it pullses. I think that the sound from pipes is a little bit louder. When I'm riding I feel that the engine misses. Waht more. It is very hard to set the revs. When I pull enrichener and I set reasonable revs than when I push knob in the engine stops. When I set the revs without enrichener and than I pull it out the revs are high. Before I do not have this type of problem. Maybe it suggests that I have air leak in manifold. I hope tomorow I will have new manifold gaskets so I will change it.
But on the other hand I do not have a tachometer so I tested revs using electronic tachometer that is clipped to the spark plug wire. This electronic tach is not working really good so I'm not sure it's readings. It sometimes showed 0 while engine was idling, but sometimes about 700-800, while I'm sure (because I know the engine sound) that it was about 1000 revs. So it could suggest that there is electric problem. But as I said this electronic tach is working a little bit strange and I do not trust it. I tested it on the car and it showed values from 1900 to 5300 while engine had about 1800 rpm.

Sorry for this long reply. I'm so upset that from more than a week I can not figure out the problem.

Do you think should I change these manifold gaskets. As I wrote in first post when I recognized problems with bike the manifold screws were not tightened. I tightened them about 2 revolutions. Do you think that the gaskets are destroyed?

Any other ideas? Of course there can be a problem with ignition. But the only tests I perform were just looking at module. When I on the bike the diode blink one time what suggest that self test is OK. And I looked at TDC and exactly when I reach TDC in hole the diode goes out so it is also OK.

 

[Hoople]

Do you think should I change these manifold gaskets. As I wrote in first post when I recognized problems with bike the manifold screws were not tightened. I tightened them about 2 revolutions. Do you think that the gaskets are destroyed?

Any other ideas? Of course there can be a problem with ignition. But the only tests I perform were just looking at module. When I on the bike the diode blink one time what suggest that self test is OK. And I looked at TDC and exactly when I reach TDC in hole the diode goes out so it is also OK.

I can't be much help to you regarding the carburetor and the issues surrounding them. I know very little about slide Mikuni carbs. I replied to your thread with the hopes of separating ignition issues from everything else. Having an Ultima ignition makes it a little harder because it's a brand I am not familiar with. I was thinking your ignition may have been factory HD.

This much I can tell you. The highest demands on the coil is during wide open throttle That is why I asked you about a WOT pull in a tall gear. If the coil can supply the required voltage for that, chances are there is plenty of spark duration and available voltage for no load idle speeds. Granted that says nothing of the ignition trigger module and timing components surrounding them.

Hopefully others more knowledgeable on carbs will chime in. From what you said in your last post, I don't feel it's a coil issue.

 

[Piotra]

Hello
I was thinking what kind of lubricant or sealant should I use during intake manifold assembly. I will have new intake manifold seals. I have something like this:
Apiezon L Grease: Silicone-Free, Halogen-Free Ultra High Vacuum Grease
Would it be good to put some of this grease on seals? I do not have any silicone spray. Anybody used this kind of grease for bike?
And the second problem is that I do not have new intake rubber flange for Mikuni Carb. It can take some time to order so I'm thinking about reuse this what I have now. It looks like this:
http://www.phatperformanceparts.com/photos/42-6230.jpg
Should I put some high temp silicone on the manifold in place where the rubber flange is mounted?

 

[fin_676]

For the manifold gaskets any sealant that you may wish to use should be a high temperature sealant although the intake manifold gaskets are normally fitted dry if i was to use any type of additional sealant i would use a thin coating of hylomar blue
Universal Blue
for the carb to flange i would use some silicone grease but only a very small amount although i have mine fitted dry
I do have the hsr42 on 2 of my bikes but i am using the stock intake manifold and seals and have had no issues with that setup
It may be worth using a wee bit of loctite blue on the manifold screws to hold them tight once you reassemble

Brian

 

[Piotra]

I think I fixed the bike
I installed new intake manifold gaskets and I cleaned carburetor. Now the bike has very nice idle and is running well. During cleaning carb I reset pilot air screw to factory settings. But it seems that acceleration is flat. I know that it can be caused by my open stright pipes but I think before my bike broke and I fixed it the bike was running better. So I'm sure that it need some tuning.
I have a question about Pilot Air Screw in Mikuni HSR42. There is tunning manual for it:
http://www.mikuni.com/pdf/hsr_tuningmanual_021003.pdf

Do you have any experience in tuning of this carb. If yes write how you set this pilot air screw (how many turns from bottomed position you have). And the most importatn question. When I screw it in than the mixture become more rich and when I screw it out the mixture is become more lean or the other way.

Any advice about tunning HSR42 are much appreciated. I know that most I can read from tuning manual but sometimes theoretical and practical knowlede are different.

Best regards, Piotr

 

[fin_676]

The pilot air screw will only adjust the fuel air mix at idle and will have no affect on acceleration the area to look at during acceleration is the operation of the accelerator pump

Brian

 

[Piotra]

I tried to tune carb and it's very strange.
Before my problem with bike I have tuned carb (Mikuni HSR42) in bike and pilot air screw was set at 3/4 turn from bottomed position. I tuned the carb like is described in Mikuni Manual and at this position the idle was very good (flat, equall) and rpms were about 950-1000, the acceleration was also OK. I have to say that it is possible that I could have air leak by vacuum fitting. But always the spark plugs were black (not oily). And I never used an equipement to measure lambda or CO.

Now after fixing the bike I sealed the vacuum fitting. I cleaned carb and changed intake manifold seals. And I tried to tune carb, I started from factory settings. I have the RevTech 100 which comes with this carb. I have stright open pipes what can be a problem.
When I tried to do exacltly like is described in Mikuni manual it not work. I set the pilot air screw two turns from bottomed position. When I screw it (at 1 turn from bottomed position) the idle slows and become irregular, when I screw it out the idle fasten a little bit (at 3 and 4 turns from bottomed position). The most interesting is that at the 2 turns from bottomed position the idle seems that are obout 900-1000 but when I checked it using two ways (by measuring on spark plug wires and by measuring using laser - I can do that because I have open belt so I can put the mark on engine pulley) the rpms were .... about 700 rpm. The idle was very nice, not slow, very flat, very equal!!! But the accerelation during ride was poor.
I tested CO, HCC and lambda and again it was strange. There were some differences between pipes but:
CO was between 3 and 4.5%, HCC very high (2000-3000!) and lambda about 1.3!!! When I tried adjust the pilot air screw out the lambda was even 1.4 - the mechanic told me that the engine could not work at this value but my bike has very nice idle. So I tried adjust screw in and that the idle becomes slower and irregular so I had to risen it but the lambda was 1.15. That the equipement stops working and didn't show lambda anymore :small3d031:

So I leaved the pilot air screw adjusted one turn from bottomed position. The idle was a little bit worse than before but when I tested it it was 850-900 rpms!!! And I took very short ride and I have to say that the bike now is runnung very well. It accelerates really fast. I now that I have to tune it more again (I have to go to other shop and use other equipement).

What do you think about it. Huge HCC and lambda indicates very lean condition at factory settings. I think that better readings can be obtained when the screw is one turn from bottomed position but than idle is irregular. I have to tested it again.

For me all is very strange!!! :small3d031:

 

[Hoople]

I tested CO, HCC and lambda and again it was strange. There were some differences between pipes but:
CO was between 3 and 4.5%, HCC very high (2000-3000!) and lambda about 1.3!!!

Actually that is really not that high. 4% CO is about 13 to 1 air fuel ratio on non-alky gas. On a non emission carb bike, that's about what I would adjust to (at idle) running 10% alky. (factor .3 of 1 ratio point for 10% alky) So 13.0 to 1 @ 10% alky is about equal to 13.3 to1 @ pure non alky.

Now the HC is crazy high (2000 PPM). There is raw fuel coming out the pipes that is not being burned.. Spark duration may not be long enough. If you can,, advance the spark timing at idle. That may help. Is the compression up to spec?
Even running an air/fuel ratio of 13 to 1 should not make HC go that high. I would fix that first.

 

[Jack Klarich]

Run a compression test on this motor just for grins, that and a weak spark may be the problem