Blocking cylinder oil injection off

[Craighjr]

Still having oil fouling issues. It’s been years and I really want to get the bike rideable. Could I just put bolts in the 3 oil feeds to the cylinders intake ports to block the oil? Run premix for the intake oil and cci for the crank bearing oil?

[jabcb]

Did you do anything more beyond your forum posts of last year?
viewtopic.php?f=2&t=13876&p=175521#p175521

You mention getting an eBay pump. Did that pump come with the actuator arm installed? And what is the number stamped on the arm?

[Craighjr]

Funny I never saw that post as I gave up on the bike again...I don’t remember what the pump was listed for but I do have a very twisted up arm that I believe came on that pump with me here at work right now. It’s marked 341. I’m pretty sure that how the arm being 180 out came to be as this arm was twisted beyond use.

[Alan H]

Still having oil fouling issues. It’s been years and I really want to get the bike rideable. Could I just put bolts in the 3 oil feeds to the cylinders intake ports to block the oil? Run premix for the intake oil and cci for the crank bearing oil?

No. It's a piston pump and will over pressure the lines and burst them.

[jabcb]

pump part #s:
73 GT750: 16100-31002
75 GT750: 16100-31202

73 GT550: 16100-34001
75 GT550: 16100-34101

73 GT380: 16100-33001
75 GT380: 16100-33100

Looked on eBay. A GT750 pump is stamped 310
My 72 GT380 pump is stamped 33X (can’t read the 3rd digit)

Your pump is actually for a GT550. It delivers too much oil for your GT380.

What was wrong with you original GT380 pump?

[Craighjr]

The center where the seal rides rusted up. The seal was trashed and the oil leaked right out and into the trans.

[Craighjr]

Trying to post a photo because photobucket doesn’t work anymore...
https://i.ibb.co/0jZ2N5T/F3-E3-E49-F-D ... 2823-D.jpg
The arm, now straightened, is clearly different. Positive the internals are different? I would rather not take it apart to measure the pistons, spring and bore depths.

[daxman]

Why are you so sure it's oil fouling the plugs? What's the exhaust smoke like when warm? Still billowing blue clouds or just a haze?
Ignition misfire can cause fouling too.

[jabcb]

The pumps are likely internally different. The GT380 & GT550 pumps have different flow rates at idle & at full throttle.
Do not mix up which are goes on which pump.

Which pump did you take apart? And why?

You can get a new gasket that is the correct thickness. So you can reassemble that pump.

[Craighjr]

I have a bunch of smoke with modern 2 stroke oil. The plugs get gunky and the bike starts dropping cylinders after 4-5miles. I put in new plugs and it runs well again for 4-5 miles. The ignition is a Power dynamo that seems to be working well. With new plugs the bike starts easily and idles well once warmed up.

My original 380 pump is apart. The lower seal had a ring of rust on the inner spindle so the oil leaks right through it. It’s arm is marked 330. The replacement pump I sourced I believe to be a 380 pump came with a 341 arm bent to hell so I didn’t use it. I know I can get the top gasket so I guess I will take the current pump I’m using apart to find out if they are really different or if it’s all in the arm to change flow rates.

[daxman]

I have a bunch of smoke with modern 2 stroke oil. The plugs get gunky and the bike starts dropping cylinders after 4-5miles. I put in new plugs and it runs well again for 4-5 miles. The ignition is a Power dynamo that seems to be working well. With new plugs the bike starts easily and idles well once warmed up.

Fair enough. Might be worth getting someone to follow you to check how bad it is. Although my bro once had a ragged Jawa/CZ 250 that billowed blue smoke but didn't foul the plugs as far as I know. Maybe also try a hotter plug NGK 7 or 6 grade?

My original 380 pump is apart. The lower seal had a ring of rust on the inner spindle so the oil leaks right through it. It’s arm is marked 330. The replacement pump I sourced I believe to be a 380 pump came with a 341 arm bent to hell so I didn’t use it. I know I can get the top gasket so I guess I will take the current pump I’m using apart to find out if they are really different or if it’s all in the arm to change flow rates.

Good plan.

[larryd]

Has anyone tried blocking off the cylinder cci inlets and then plumbing the three cylinder injection lines back to the reservoir while still letting cci feed the main bearings? The pump can't tell the difference so the lines won't burst. I can then run premix and have more control over the ratio, reducing fouling and the James Bond smokescreen.

[Alan H]

https://www.oldjapanesebikes.com/mraxl_ ... s/page-A57 is worth a read. Going premix is not recommended as the big ends have 'flingers' which throw oil under the pistons to the little ends and onto the cylinder barrels. The bearings will be starved of oil and fail.
Fit the correct pump and plugs, and time the bike as Suzuki recommends. All my 550s are on standard plugs, coils and ignition and timed to the 'propeller' marks behind the points plate and run well.

[karl pa]

There is a member on this forum who drag races GT750, I remember he said he eliminated the cylinder feed but kept the bearing feed, and ran premix for cylinder. I don't know how he blocked off the cylinder feeds.
If the bike fouls plugs and leaves a smoke screen, it could be signs of other trouble.