stuard
L plate rider.
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Post by stuard on Oct 18, 2022 20:43:31 GMT 1
Hi all.
I recently picked up a refurbished 1974 RD350A, it ran very rich but carbs were overflowing. Managed to sort by stripping etc, but bike now won't start at all.
Suspect flooding fuel into the engine, garage mechanic suspects a worn choke plunger.
Bike has low mileage, plus I changed the choke plunger O ring, as it was perished.
Has anyone got any ideas?
Can u corroborate this theory?
Can't find plungers in UK either, know of any?
Would have to pay a fortune for a small part from USA, but just want it sorted.
Any help appreciated.
TiA
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Post by chrisg on Oct 21, 2022 21:17:31 GMT 1
How did u stop the leak?
Check the float height, it can make a big difference. If the engine is flooded, remove the plugs and kick it over several times. Put a old tea shirt over the plug holes to stop any fuel coating the frame.
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Post by cbm on Oct 22, 2022 7:08:27 GMT 1
Hi all. I recently picked up a refurbished 1974 RD350A, it ran very rich but carbs were overflowing. Managed to sort by stripping etc, but bike now won't start at all. Suspect flooding fuel into the engine, garage mechanic suspects a worn choke plunger. Bike has low mileage, plus I changed the choke plunger O ring, as it was perished. Has anyone got any ideas? Can u corroborate this theory? Can't find plungers in UK either, know of any? Would have to pay a fortune for a small part from USA, but just want it sorted. Any help appreciated. TiA Rob's the Guy you need to speak to. He can replace the seal at the bottom of the choke plunger for you which, if diagnosed correctly, should solve your problem đź‘Ť - rdlccrazy.proboards.com/thread/54645/plunger-replacement-service-mikuni-keihin |
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Post by reedpete on Oct 22, 2022 9:18:01 GMT 1
The plunger seal is likely to be worn… they all are now…
But that’s not what’s causing flooding ( can’t cause flooding) or stopping it from starting…
Suggest, go back to the beginning and step by step work through.
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Post by tony2stroke on Oct 22, 2022 10:45:05 GMT 1
You say it was running rich but carbs overflowing, you stopped it overflowing and now won't start, as asked above, how did you stop overflowing.
If carbs overflowing, this will make it rich, the float height is important, too low and not enough fuel making mixture lean and hard to start, or even not start at all.
As has been said, go through carbs again and check everything is in correct order.
Again as has been said, damaged plunger rod seal won't stop it starting, if badly damaged seal, then it would just act like choke on or partially on all the time and cause trouble once warming up and warmed up.
Make sure the throttle slides are in the correct carbs (cut out facing you) and make sure you have any pipes connected between carbs, made that mistake myself, forgetting to connect choke pipe on rd200, bike would not start and it was not obvious I hadn't connected it being out of sight.
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stuard
L plate rider.
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Post by stuard on Nov 6, 2022 20:59:03 GMT 1
For information....
Bike is back from garage, starts and runs fine after repairing rubber stopper started plunger. Perhaps didn't help that I put in Air filter wrong way round....der...
New issue is drip (1 everyv4 secs) from the lower overflow on RH carb. I assume the float height needs adjusting.
The mechanic did not fit the overpipes to the lower drains, but instead to upper fittings.
Does anyone know what pipes should be fitted to what fittings?
The manual I have does not say anything about them.
TiA
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Post by reedpete on Nov 6, 2022 21:48:09 GMT 1
It won’t be float heigh that’s causing the drip…. Could be several things.. most likely is just crud in the float valve.
Regards which tubes where….I think the first thing you should do is check the type of carb you have fitted, because the spigots vary according to type and after so many years it’s quite possible you don’t have the correct ones.
Look for numbers stamped into the choke boss. Looking for one of the following 360/361/522/1A2
you should have 361-92 if it’s a baffled uk 250A.
its not a show stopper If they are not 361-92 , as they can all be configured to suit.
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stuard
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Post by stuard on Nov 8, 2022 16:48:32 GMT 1
It won’t be float heigh that’s causing the drip…. Could be several things.. most likely is just crud in the float valve. Regards which tubes where….I think the first thing you should do is check the type of carb you have fitted, because the spigots vary according to type and after so many years it’s quite possible you don’t have the correct ones. Look for numbers stamped into the choke boss. Looking for one of the following 360/361/522/1A2 you should have 361-92 if it’s a baffled uk 250A. its not a show stopper If they are not 361-92 , as they can all be configured to suit. |
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stuard
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Post by stuard on Nov 8, 2022 16:54:46 GMT 1
Done some checks....
Carbs are 360-02, so right for a 350.
Tap not leaking into carbs when closed.
When set to On, leak rate increases, but stops when engine running.
Tried the 'tap' on the carb, and the 'thrash it' tricks all to no avail.
Need to dismantle again and check internals.
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Post by tony2stroke on Nov 8, 2022 18:30:50 GMT 1
Check the needle valve and valve needle for wear or damage, if they look ok, try a little polish (autosol or similar) put some on a cotton bud and twist it in the needle seat (brass bit) make sure you remove any residue of polish, then some polish on a rag and polish the tip of the needle by twisting in the polish on the rag, again remove any residue polish, this can solve the issue sometimes, but if any wear on either part they need replacing.
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stuard
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Post by stuard on Feb 6, 2023 22:33:40 GMT 1
Still issues with my carbs....
Got back from garage, carbs were stripped, set and cleaned etc.
Has been periodically started ok in my garage, but last week took for a ride, and ended running on 1 x pot (now fixed with new plugs), and continuous flow from LH lower overflow drain.
Crap in the carb you reckon?
Any other ideas?
TiA
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Post by abar121 on Feb 7, 2023 21:42:34 GMT 1
Still sounds like the needle valve and seat is at least part of the problem..
Take the carb off and try filling it on the bench.
Is the tank clean inside?
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Post by reedpete on Feb 8, 2023 15:04:15 GMT 1
These old girls need some sympathy no matter how much work has been done with them…
Old carbs are old carbs, tank will inevitably have something in it, fuel tap and gauze only stops certain amount of stuff.
The floats on those early carbs slide up and down pillars, so when on the side stand they are not vertical and with inevitable corrosion on the inner of the tube going through the float, it all contributes to the situation.
What I normally do on these and LC, is just to switch the fuel off whilst bike is running so that the bowls empty and the float valve is fully open. Then turning the tap back on will often flush debris and or cycle the float mechanism.
If it persists, just strip and clean and start again. After a rebuilt it can often take a bit of settling down to rid of such gremlins.
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crigar
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Post by crigar on Mar 2, 2023 18:40:39 GMT 1
It's possible that the floats are no longer watertight. To check, take them out of the carburetor and shake them to hear if there is no fuel inside.
Il est possible que les flotteurs ne soient plus étanches. Pour vérifier il faut les sortir du carburateur et les secouer pour écouter si il n'y a pas d'essence à l'intérieur.
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stuard
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Post by stuard on Mar 3, 2023 11:15:49 GMT 1
Still sounds like the needle valve and seat is at least part of the problem.. Take the carb off and try filling it on the bench. Is the tank clean inside? |
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stuard
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Post by stuard on Mar 3, 2023 11:19:41 GMT 1
Tank had been cleaned inside, new tap, but still a little residue found in the tap bowl.
I took off carb, no real crap in there of note, Che ked all in order, reassembled and refitted on bike.
Now working, no overflow issue.
Got another problem tho.... Will do a separate thread.
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stuard
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Post by stuard on Mar 3, 2023 11:21:37 GMT 1
These old girls need some sympathy no matter how much work has been done with them… Old carbs are old carbs, tank will inevitably have something in it, fuel tap and gauze only stops certain amount of stuff. The floats on those early carbs slide up and down pillars, so when on the side stand they are not vertical and with inevitable corrosion on the inner of the tube going through the float, it all contributes to the situation. What I normally do on these and LC, is just to switch the fuel off whilst bike is running so that the bowls empty and the float valve is fully open. Then turning the tap back on will often flush debris and or cycle the float mechanism. If it persists, just strip and clean and start again. After a rebuilt it can often take a bit of settling down to rid of such gremlins. |
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stuard
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Post by stuard on Mar 3, 2023 11:22:29 GMT 1
Thanks, that's pretty much what I've been doing.
See my previous thread answer.
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stuard
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Post by stuard on Mar 3, 2023 11:23:23 GMT 1
It's possible that the floats are no longer watertight. To check, take them out of the carburetor and shake them to hear if there is no fuel inside. Il est possible que les flotteurs ne soient plus étanches. Pour vérifier il faut les sortir du carburateur et les secouer pour écouter si il n'y a pas d'essence à l'intérieur. |
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stuard
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Post by stuard on Mar 3, 2023 11:25:06 GMT 1
Merci.
I stripped and cleaned carbs and bench checked that floats worked.
Reassembled and no overflow issue now.
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