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91' DR350 No Start, Bump Start Okay, Runs Rich

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I am just unable to get this beast going again.

day it died: was riding on trail. stop to take a break. bike stalled. never started again. 

we had no spark. replaced trigger coil. have spark. still no start.

I think the carb is a Mikuni TM36 or 38.

 

Other checks:

I have tested resistance of pulsar coil and ignition coil.

Timing should line up. Magento lined, Cams pointed opposite of each other. the up arrow with a 1 next to it on the cam sprocket.

Woodruff Key

Carb cleaned

new spark plugs


 

Yesterday: Was able to bump start it but didn't feel right. Almost like misfiring. Couldn't hold anything less than 1/4 throttle. Even then having to give a bit more throttle to keep it going.

 

Engine had a misfire sound to it. You can feel it by placing hand over the exhaust. You feel the brief cut out even at 1/2 throttle.

Plug was completely covered in dry black soot.

Carb main jet needle(i think) is currently set to the middle notch.

Valve clearance on the intake was on the high end of spec with some drag. I can't recall exhaust valves but I believe they were within the min/max

 

I could take it to the shop but I am more interested in learning on this bike. I bought it (with plate) for $200 so it has been more of a project.

Edited by 805Barbarian

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I am just unable to get this beast going again.
day it died: was riding on trail. stop to take a break. bike stalled. never started again. 
we had no spark. replaced trigger coil. have spark. still no start.
I think the carb is a Mikuni TM36 or 38.
 
Other checks:
I have tested resistance of pulsar coil and ignition coil.
Timing should line up. Magento lined, Cams pointed opposite of each other. the up arrow with a 1 next to it on the cam sprocket.
Woodruff Key
Carb cleaned
new spark plugs

 
Yesterday: Was able to bump start it but didn't feel right. Almost like misfiring. Couldn't hold anything less than 1/4 throttle. Even then having to give a bit more throttle to keep it going.
 
Engine had a misfire sound to it. You can feel it by placing hand over the exhaust. You feel the brief cut out even at 1/2 throttle.
Plug was completely covered in dry black soot.
Carb main jet needle(i think) is currently set to the middle notch.
Valve clearance on the intake was on the high end of spec with some drag. I can't recall exhaust valves but I believe they were within the min/max
 
I could take it to the shop but I am more interested in learning on this bike. I bought it (with plate) for $200 so it has been more of a project.


How many pickups does the stator have? 1 or 2? Is this a dirt model bike?

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6 minutes ago, hscarborough said:

 


How many pickups does the stator have? 1 or 2? Is this a dirt model bike?

 

I am pretty sure it is a Street model. However no battery. I am the third owner as far as I know.

 

 

t is this fella: 21-817.jpg

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I am pretty sure it is a Street model. However no battery. I am the third owner as far as I know.
 
 
t is this fella: 21-817.jpg


Is that the stator you installed? If so, then it's a single pickup street model. The dirt model only has about 1/3 of the windings. The later models used a double pickup design so one of the handled the high RPM sparks and the other handled low RPM. So I was wondering if your low RPM pickup had gone out and was causing your issues. But if your one and only pickup went bad then I suspect you would get no spark at all. There goes that idea...

As a side note, be sure to tape up your battery connectors if they are just flopping around. You wouldn't want the + and - to accidentally touch.

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1 minute ago, hscarborough said:

 


Is that the stator you installed? If so, then it's a single pickup street model. The dirt model only has about 1/3 of the windings. The later models used a double pickup design so one of the handled the high RPM sparks and the other handled low RPM. So I was wondering if your low RPM pickup had gone out and was causing your issues. But if your one and only pickup went bad then I suspect you would get no spark at all. There goes that idea...

As a side note, be sure to tape up your battery connectors if they are just flopping around. You wouldn't want the + and - to accidentally touch.

 

I havent had the stator replace... I just thought it would be easier to visually tell you what is in the bike.  I had just replaced the pick up coil only when I lost spark. People have different names for it but I used Trigger Coil.  I didn't do the no battery mod but I inspected all the wiring and retaped worn out areas. Maybe a full inspection is needed?

Doesn't seem like valves would be the issue..maybe?

 

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Doesn't seem like valves would be the issue..maybe?
 


Didn't you already check the valve clearances? You can do a simple compression test or a leak down test. Beyond that, there is little checking you can do besides pulling the head off and visually inspecting them.

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20 minutes ago, hscarborough said:

 


Didn't you already check the valve clearances? You can do a simple compression test or a leak down test. Beyond that, there is little checking you can do besides pulling the head off and visually inspecting them.

 

Ill check em again and write all the sizes down. Shouldnt take long

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1 hour ago, hscarborough said:

 


Didn't you already check the valve clearances? You can do a simple compression test or a leak down test. Beyond that, there is little checking you can do besides pulling the head off and visually inspecting them.

 

 

Intake .10 MM with drag, going up to .13mm didnt fit.

Exhaust was .13mm and going up to .15mm didnt fit.

the Intake is either just slightly out of spec or just about to be.

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Intake .10 MM with drag, going up to .13mm didnt fit.
Exhaust was .13mm and going up to .15mm didnt fit.
the Intake is either just slightly out of spec or just about to be.


Those sound fine. I still believe your issue is electrical. Either the CDI, ignition coil, or pickup coil... Just a hunch.

It's important to remember that with wear these numbers are actually going to get SMALLER, not bigger. The reason being that as the valves wear into their seats (the flat plunger part where the combustion happens) then the stem will come further up towards the tappets and make that gap tighter.. So it's best to be on the larger end of the spec to allow for the maximum service interval.

Spec says

Intake: 0.05-0.10mm
Exhaust: 0.08-0.13mm

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35 minutes ago, hscarborough said:

 


Those sound fine. I still believe your issue is electrical. Either the CDI, ignition coil, or pickup coil... Just a hunch.

It's important to remember that with wear these numbers are actually going to get SMALLER, not bigger. The reason being that as the valves wear into their seats (the flat plunger part where the combustion happens) then the stem will come further up towards the tappets and make that gap tighter.. So it's best to be on the larger end of the spec to allow for the maximum service interval.

Spec says

Intake: 0.05-0.10mm
Exhaust: 0.08-0.13mm

 

I think I may of found the culprit.

Pickup Coil resistance is 300+ where the service manual says 270.

 

I still have the CDI to test but will do ASAP.

Edited by 805Barbarian

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I think I may of found the culprit.
Pickup Coil resistance is 300+ where the service manual says 270.
 
I still have the CDI to test but will do ASAP.


The difference between 270 and 300 doesn't seem significant but you added a "+" to the 300 so hopefully that means it was much higher. The CDI is virtually untestable by regular garage means. Needs to be hooked up to a fancy machine to be tested if I remember right. (The manual will say)

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19 hours ago, hscarborough said:

 


The difference between 270 and 300 doesn't seem significant but you added a "+" to the 300 so hopefully that means it was much higher. The CDI is virtually untestable by regular garage means. Needs to be hooked up to a fancy machine to be tested if I remember right. (The manual will say)

 

It was like 318.

I have a buddy bringing me a endoscope to check out the piston and intake valves.

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12 minutes ago, hscarborough said:


Any update?

my buddy bailed and waiting for a new coil. I going on vacation so it might have to wait if it does not arrive soon.

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