Can't get it running

[Farmjohnny]

Perhaps this will help.

FYI, 3-5 psi will usually do the trick.

https://www.youtube.com/watch?v=zdq7NRcUIp8

Tom

[Andreas Piepke]

Hi All,

Today I heeded Michael's words and installed a ground line from the coil to the engine:



The copper braid gives a very low resistance current return now (verified with an ohmmeter). Michael I admit it: the engine does start easier now! Thanks for your suggestion.
One down, one to go: the engine still runs weak. I changed the number of disks in the Super Trap from 8 to 4 and found that the engine runs worse. So I will go to 6. By now I tried just about anything to get the engine running well but without real success. I probably will have to do the leak test describer in this thread. However, I don't have the tools and will have to rig-up a pump with pressure gauge (have that). I will also need to find appropriate plugs to block inlet and outlet, I don't have those. If this doesn't work then I'll probably have to take the engine back out and apart. I hope I won't have to do that!

Thanks for all your guidance it certainly helps!

Cheers

Andreas

[Mick Milakovic]

Andreas, you've certainly been very methodical in your approach and have received a lot of good advice.  By no means am I an expert builder or rider, but something in your video test caught my attention.  It could be simply the sound and method of your shifting, but there were several times when your engine noise sounded like a slipping clutch.  A slipping clutch would definitely keep the engine from performing properly.  My 250 has a ton of acceleration and can lift the wheel in several gears.  

Again, it could have been your shifting style (and using the clutch) but it had that sound. Also, I'm no expert at adjusting the Penton clutch, so I can't give advice on that.  I just cringe at the thought of you pulling the motor apart without inspecting that option.  How do you feel the clutch set-up is?

Mick

[Andreas Piepke]

Hi Mick,

I don't think the clutch is slipping. I gave plenty of play to the mechanism, to a degree where I need to elevate the revs when engaging first gear to prevent the engine from dying. I did this exactly for the reason you mention: see whether the clutch is slipping. There seems to be no relation between test running the bike with more or less clutch play. The thought of taking the engine out again makes me cringe too! I certainly hope it won't be needed.

Thanks for sharing your observation with me

Andreas

[Daniel P. McEntee]

To plug the exhaust and the intake, just go to the plumbing department of the hardware store and look for expandable rubber plugs in the size you need. You are only talking about 5 psi or so for this application so mo real need for anything more. Auto parts stores carry them also to replace freeze plugs. I even made one out of rubber hose and a carriage bolt one time to make a drain plug for my '75 Husky after the threads stripped out for the stock drain plug!
  I'll be watching for updates and improvements.
  Type at you later,
   Dan McEntee

[Andreas Piepke]

Hi All,

I do see a spark when I remove the plug. I didn't add a current return cable yet but did measure the resistance from the coil mounting to the engine when Michael pointed this out. I found good continuity then. The coil mounting tabs are not painted and the engine mounting bolts are all new and not corroded. Perhaps at this point I should follow Michael's advice, it's easy enough to do and eliminates one uncertainty. Yes indeed the ignition was load tested and the fly wheel re-magnetized. The ignition itself should be in good shape. I also have a new NGK spark plug of the recommended type.

For this vacuum test is there a description of the procedure somewhere? Do I need to take the carburetor and exhaust off for this so I can seal them?
I just read through the new thread on Super Trap exhaust. I'll certainly try to reduce the number of disks from now 7 to 4.
Just to be clear, I am battling with two different but perhaps related problems: (1) difficulty starting the engine, (2) low engine performance. This thread of posts kind of mixes these two issues.

Thanks for your input!

Andreas

[fischercycle]

HIGH ANDREW, My x wife just told me the reason she left me was because I did not have any SPARK left to kick it hard ENOUGH, TO GET IT STARTED,MAYBE GIVE THAT A TRY,THANKS JAKE

[454MRW]

Andreas,
I feel you are not understanding the grounding of the ignition on the Penton.
The bolts have nothing to do with the ground except to keep the engine tight in the frame. The ground is between the inside of the frame mounts to the outside of the engine cases, and the coil mount to the mounting tab on the frame. Unless you have physically ground off the paint from the inside of those mounts and also on the engine mount bosses, you do not have proper ignition grounding. Period.
Do yourself a favor and install the ground wire from the coil mount bracket, (sand the connections to shiny metal) and run the other to a clean shiny metal point of the engine. you can always run it to the actual stator plate later to even improve the path. Then ride the bike and see if there is a difference with no other changes. It doesn't matter that the ignition is tested or you see a good spark. Mike

Michael R. Winter
I enjoy rebuilding and appreciating Pentons!
1974 250 HS Pentons-1980 KTM 175-400'S
1975 Can Am 175 TNT & 77 250 Black Widow
1979 Husqvarna OR390
1976-78 RM & 77-79 PE Suzuki's
1974 CR250M 07 CR125R 79 CR250R

[Farmjohnny]

As Michael said, just because you can see a spark it means very little. In A&P school we would test plugs that looked fantastic till you added a bit of cylinder pressure and watch them go dead. Same with coils.

Add the jumper.

Tom

[Farmjohnny]

I have some experience with testing under vacuum, but with these I prefer to test under pressure. It exposes the components (seals and such) too the same loads that occur under normal operation.

[Farmjohnny]

Perhaps this will help.

FYI, 3-5 psi will usually do the trick.

https://www.youtube.com/watch?v=zdq7NRcUIp8

Tom

[Andreas Piepke]

Hi All,

Today I heeded Michael's words and installed a ground line from the coil to the engine:



The copper braid gives a very low resistance current return now (verified with an ohmmeter). Michael I admit it: the engine does start easier now! Thanks for your suggestion.
One down, one to go: the engine still runs weak. I changed the number of disks in the Super Trap from 8 to 4 and found that the engine runs worse. So I will go to 6. By now I tried just about anything to get the engine running well but without real success. I probably will have to do the leak test describer in this thread. However, I don't have the tools and will have to rig-up a pump with pressure gauge (have that). I will also need to find appropriate plugs to block inlet and outlet, I don't have those. If this doesn't work then I'll probably have to take the engine back out and apart. I hope I won't have to do that!

Thanks for all your guidance it certainly helps!

Cheers

Andreas

[Mick Milakovic]

Andreas, you've certainly been very methodical in your approach and have received a lot of good advice.  By no means am I an expert builder or rider, but something in your video test caught my attention.  It could be simply the sound and method of your shifting, but there were several times when your engine noise sounded like a slipping clutch.  A slipping clutch would definitely keep the engine from performing properly.  My 250 has a ton of acceleration and can lift the wheel in several gears.  

Again, it could have been your shifting style (and using the clutch) but it had that sound. Also, I'm no expert at adjusting the Penton clutch, so I can't give advice on that.  I just cringe at the thought of you pulling the motor apart without inspecting that option.  How do you feel the clutch set-up is?

Mick

[Andreas Piepke]

Hi Mick,

I don't think the clutch is slipping. I gave plenty of play to the mechanism, to a degree where I need to elevate the revs when engaging first gear to prevent the engine from dying. I did this exactly for the reason you mention: see whether the clutch is slipping. There seems to be no relation between test running the bike with more or less clutch play. The thought of taking the engine out again makes me cringe too! I certainly hope it won't be needed.

Thanks for sharing your observation with me

Andreas

[Daniel P. McEntee]

To plug the exhaust and the intake, just go to the plumbing department of the hardware store and look for expandable rubber plugs in the size you need. You are only talking about 5 psi or so for this application so mo real need for anything more. Auto parts stores carry them also to replace freeze plugs. I even made one out of rubber hose and a carriage bolt one time to make a drain plug for my '75 Husky after the threads stripped out for the stock drain plug!
  I'll be watching for updates and improvements.
  Type at you later,
   Dan McEntee