Dnepr MT9 difficult start

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Jager
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Dnepr MT9 difficult start

Post by Jager » Mon Oct 15, 2018 12:22 pm

Hi I`mNew here
My MT9 have some issue Can any one help me.
Engine in work
Right cylinder Before the start of the occasional carburetor will be anti-spray, starting after the accelerator line has an acceleration reaction, the suction force of the hand block intake is strong, the late increase in idle speed can not be lowered (in the third film may be heard), after the removal of the Mars Plug and Operation stopped.
Left cylinder Pull spark plug does not react, hand block intake suction weak, after the removal of the Mars Plug and operation will not stop (right now in the cylinder running
Dual-cylinder spark plug Normal
The left cylinder of the carburetor is still suspected of not working, the carburetor suction is strong, the throttle did not respond. The following treatment has been done, but there has been no improvement in the start-up difficulties. Cleaning and inspecting the carburetor Reversing the Carburetor Adjusting the valve spacing (0.10mm) Pour a little oil to the left cylinder, run and then stop.

Cylinder pressure Heat car after the cylinder pressure around the same about 50PSI

Dose any know How to set up this Ignition?My MT9 fiywheel mark are different some like 一 ㄈ 一 一. there are no arrow mark ->
Did I set wrong time?
Cheers

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https://youtu.be/1gAgkisHT28
https://youtu.be/miEbjqJo4Ww

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propwash
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Re: Dnepr MT9 difficult start

Post by propwash » Tue Oct 16, 2018 11:08 am

50PSI is low and indicates a problem. Is the pressure the same on both right and left?

I have not seen flywheel markings like that before and I have bee exposed to nearly all type of Soviet motos from M72, M61, K750, M63, MT10, MT16...
MT9, K650 rare here.

I would try by assuming first mark (when rotating) is ignition (full advance) mark. Second mark is TDC for setting valves.

Udachi!

GregAus
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Re: Dnepr MT9 difficult start

Post by GregAus » Wed Oct 17, 2018 10:44 pm

MT-9 is a 6V system, your photo shows an electronic 12V system. Some will work down to 6V, but not all. Also 50 PSI is very low. The «П» mark on the flywheel, (bottom right photo) is the ignition advance mark and should be 32-36º BTDC. Best to fit a degree wheel to the crankshaft and see what angle to various marks are at.

Jager
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Re: Dnepr MT9 difficult start

Post by Jager » Thu Oct 18, 2018 10:39 am

Hi
Thanks for reply.
yes the both side are around 50 psi. I have did some search that that should be take 7.5 and multiply by 14.7 (ambiant air) low of about 100 PSI to around 105 PSI. not more than 10% out between the pistons.A
Is that correct?
No ideal why my mt flywheel markings are different.
I also take off the Cylinder too check.I find they are no Cylinder Head gasket on both side.I thought that may caused some of leak out the pressure.
The something Weird too the Position size are 77.97MM (MT11 OR MT16) not 78MM.
The Right side Tappet rod are some damage.

Yes The electronic is 12V system the Previous Owner has been the electronic system to 12v except the Generator 6V and Regulating relay PP302.
I reset ignition at mark ㄈ.
Do I need change whole Cylinder and piston set???
Thank you guys

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propwash
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Re: Dnepr MT9 difficult start

Post by propwash » Thu Oct 18, 2018 12:24 pm

Jager wrote:
Thu Oct 18, 2018 10:39 am
Hi
Thanks for reply.
yes the both side are around 50 psi. I have did some search that that should be take 7.5 and multiply by 14.7 (ambiant air) low of about 100 PSI to around 105 PSI. not more than 10% out between the pistons.A
Is that correct?
No ideal why my mt flywheel markings are different.
I also take off the Cylinder too check.I find they are no Cylinder Head gasket on both side.I thought that may caused some of leak out the pressure.
The something Weird too the Position size are 77.97MM (MT11 OR MT16) not 78MM.
The Right side Tappet rod are some damage.

Yes The electronic is 12V system the Previous Owner has been the electronic system to 12v except the Generator 6V and Regulating relay PP302.
I reset ignition at mark ㄈ.
Do I need change whole Cylinder and piston set???
Thank you guys
Yes, you should be around 100PSI.

My MT11 ran fine for 10 years and 45,000 kms without head gaskets... I think mine came that way from factory.

Your piston size is correct, do not worry.

Generally, the low compression in these engines is from the valve system.

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Re: Dnepr MT9 difficult start

Post by GregAus » Thu Oct 18, 2018 9:01 pm

Checked the specs of the electronic ignition and it should work from 6V, however the particular coil you have is regarded as rather flakey. The 135.3705M is a better coil according to Russian forums.

First thing to do is ensure valve timing is correct and redo the compression check. Then isolate the generator and battery and try the ignition with a 12V battery. If it starts, then you know the coil doesn't like a 6V source.

Jager
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Re: Dnepr MT9 difficult start

Post by Jager » Sun Oct 21, 2018 10:47 am

Thank you Gentleman
After reset the ignition the left cylinder was working now at least 1 days ago.look like Spitfire :D :D Blue flame on exhaust. But seem the idle speed are too height.
The compression are more higher around 75 psi.
Just did adjustment of valve and will try again compression.
follow some Search video about Valve clearances.
Rotating the flywheel to mark ㄈ and adjust left side Valve clearances for 0.1mm and roll free the rod
Rotating flywheel 360 again to mark ㄈ adjust right side Valve.
Is that correct?

Yes I have put 12V battery and the spark was blue.
Indeed the one I have not good May order a of 135.3705M.
Cheers

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propwash
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Re: Dnepr MT9 difficult start

Post by propwash » Sun Oct 21, 2018 10:57 am

Your marks on the flywheel are a problem.
Take sparkplug out, place thumb over sparkplug hole and turn over engine.
When you feel pressure pushing on thumb, stop.
Place a small wooden stick in hole and tap kickstarter slowly and watch the stick and the valves.
When intake valve is closing, you are getting close to TDC. Keep tapping until stick is fully extended. Now you are at TDC.
This is where you want to set your valves to specification.
Now look at the flywheel mark. What mark is showing?
Repeat on other cylinder.

rivers
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Re: Dnepr MT9 difficult start

Post by rivers » Sun Oct 21, 2018 12:25 pm

Do I need change whole Cylinder and piston set???
Since both readings are equal it's probably just normal wear with nothing broken. You might be able to get away with just honing and new rings but you'll need to have you or a pro measure the bore for taper to determine if you need a clean-up bore or if just honing is good enough. I don't know how much of a clean-up bore IMZ/KMZ jugs can handle before you have to replace them? You'll also have to inspect/measure the pistons to know if re-using them with new rings is a good idea. What's your end goal? If farm equipt needed to just get you through harvest you might get away with just re-ring it till you have time to fix it properly. If building for longevity and normal power I would spring for new pistons. 50-75 psi is a pretty tired motor. at 75 it'll run but not near as well as it should. I'm old, gimpy and lazy and learned to appreciate the sign in my dads home shop.
"Funny, there is never enough time to do the job right, but somehow there's always time to do it over."
Joe
014 GU
"I'm lost but I'm making good time."

Jager
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Re: Dnepr MT9 difficult start

Post by Jager » Thu Oct 25, 2018 8:15 am

propwash wrote:
Sun Oct 21, 2018 10:57 am
Your marks on the flywheel are a problem.
Take sparkplug out, place thumb over sparkplug hole and turn over engine.
When you feel pressure pushing on thumb, stop.
Place a small wooden stick in hole and tap kickstarter slowly and watch the stick and the valves.
When intake valve is closing, you are getting close to TDC. Keep tapping until stick is fully extended. Now you are at TDC.
This is where you want to set your valves to specification.
Now look at the flywheel mark. What mark is showing?
Repeat on other cylinder.
Last time I did the mark show TDC at ㄈJust like GregAus said
The first mark ㄧ should be BTDC
2rd mark ㄈ TDC
3rd mark should be一 ATDC .
ignition ware funny and may be low compression.I`ll try it after Replace the k68 carburetors, piston ,ring and 135.3705M.
rivers wrote:
Sun Oct 21, 2018 12:25 pm
Do I need change whole Cylinder and piston set???
Since both readings are equal it's probably just normal wear with nothing broken. You might be able to get away with just honing and new rings but you'll need to have you or a pro measure the bore for taper to determine if you need a clean-up bore or if just honing is good enough. I don't know how much of a clean-up bore IMZ/KMZ jugs can handle before you have to replace them? You'll also have to inspect/measure the pistons to know if re-using them with new rings is a good idea. What's your end goal? If farm equipt needed to just get you through harvest you might get away with just re-ring it till you have time to fix it properly. If building for longevity and normal power I would spring for new pistons. 50-75 psi is a pretty tired motor. at 75 it'll run but not near as well as it should. I'm old, gimpy and lazy and learned to appreciate the sign in my dads home shop.
"Funny, there is never enough time to do the job right, but somehow there's always time to do it over."
Cylinder are looking good so I decide to change the piston and the ring.The goal are hope ruining good and easy Kickstart it.
indeed "there is never enough time to do the job , but somehow there's always time to do it over." :cheers:
all spear parts just order let we see what`s will happen next. 8)

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Re: Dnepr MT9 difficult start

Post by ptt007x » Thu Nov 08, 2018 10:49 pm

MT-9 is a 6V system, your photo shows an electronic 12V system. Some will work down to 6V, but not all. Also 50 PSI is very low.


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VWK75S
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Re: Dnepr MT9 difficult start

Post by VWK75S » Fri Nov 09, 2018 7:48 am

So why isn't the left carb a problem (based on the video)?
John
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