New addition to the garage…

Mailman said:
That RD350 I had back in the 70’s used to absolutely fog the neighborhood with blue smoke when I rode it. What kind of injector oil are you buying, I’ve been out of the two stroke game for a long time, I was thinking there are some brands / types of injector oil that don’t smoke as much?

On a somewhat related note, I remember this old fishing boat my dad used to have with an old Evinrude outboard , an early design it ran a very rich 12 -1 oil mix and it just about smoked you out of the boat! Years later his new Mercury outboard was running a 50-1 ratio and it was nearly as clean as a four stroke.

What I’m wondering is if maybe early two stroke motorcycles didn’t run a super rich oil mix, and smoking is unavoidable.
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MM, I’m using Amsoil Interceptor 2 stroke oil. Like any other engine oil, everyone has their favourites and this was recommended to me. Bought a lifetime supply, but in retrospect would have preferred something that had colour. This oil is a natural light amber colour.

re: outboard motors, my little 6 hp Yamaha fishing boat motor ran 100:1 (premixed) on synthetic Yamalube. Virtually smoke free although you may see a small puff on start up. When I was a kid we had a 5.5hp Evinrude that ran 16:1. Back then we didn’t have 2 stroke oil. We just used straight SAE 30 engine oil!
 
bosco659 said:
Is the 710 Motul coloured? How is it for smoke?
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If my memory serves me correctly I believe it’s the same ruby red color as the 800. Although it may be more of an Amber.

I believe the 510 is green.

When properly jetted smoke is pretty minimal. I’m my experience, when they are rich, they just smoke like a chimney.

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WideAWAKE said:
If my memory serves me correctly I believe it’s the same ruby red color as the 800. Although it may be more of an Amber.

I believe the 510 is green.

When properly jetted smoke is pretty minimal. I’m my experience, when they are rich, they just smoke like a chimney.

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Now that’s interesting. The Center cylinder likes to smoke more than the outer two. On the triple, the Center carb has one size smaller main than the outer ones. Over the years did someone put the same sized jets in all 3? I’ll be anxious to see when I rebuild the carbs. Thanks for the heads up on this.
 
Early GT750 had a scavenging system under the casings in the front of the motor, it was there to suck any excess oil out of the bottom of the crank case's back into the inlet ports, it's possible the system was dropped in later models. you could also check the adjustment on the auto lube oil pump is correct, some owners advance the adjustment so it over oils.
I had a 72 J model and that surging is normal I never got used to it but that's I was mainly a 4 stroke person.
 
T Rex NZ said:
Early GT750 had a scavenging system under the casings in the front of the motor, it was there to suck any excess oil out of the bottom of the crank case's back into the inlet ports, it's possible the system was dropped in later models. you could also check the adjustment on the auto lube oil pump is correct, some owners advance the adjustment so it over oils.
I had a 72 J model and that surging is normal I never got used to it but that's I was mainly a 4 stroke person.
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Thx. The system Suzuki came up with was named the SRIS system. Mine was a bit boogered up because the Center valve was defective. Replaced that and thought it “fixed” the Center smoking issue but it came back again. I think I’ll change the other two check valves and replace the hoses too. The auto lube is actually dialed in to deliver a little less oil than the original setting. Theory behind that is newer, modern synthetics should be able to provide adequate lubrication at higher ratios. I have to rebuild the carbs, synchronize them and add some orifices to richen the low speed circuit. Hopefully this will reduce the surging. The surging is annoying to be sure!

After I do all this work I intend to ride and enjoy the bike the rest of this season.
 
bosco659 said:
Thx. The system Suzuki came up with was named the SRIS system. Mine was a bit boogered up because the Center valve was defective. Replaced that and thought it “fixed” the Center smoking issue but it came back again. I think I’ll change the other two check valves and replace the hoses too. The auto lube is actually dialed in to deliver a little less oil than the original setting. Theory behind that is newer, modern synthetics should be able to provide adequate lubrication at higher ratios. I have to rebuild the carbs, synchronize them and add some orifices to richen the low speed circuit. Hopefully this will reduce the surging. The surging is annoying to be sure!

After I do all this work I intend to ride and enjoy the bike the rest of this season.
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your onto it, they are in my words a silky smooth bike, a real classic hang onto it.
 
T Rex NZ said:
your onto it, they are in my words a silky smooth bike, a real classic hang onto it.
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It is a great bike to tour around on. More comfortable and less vibration than the XS. Probably because of the tires but the XS seems to be more stable at highway speeds. Shame on me but I’m riding this 4x more than the XS lately. Should get the XS out for a run this weekend to make sure it’s all ready for the Paris Rally in a few weeks.
 
Are you doing butterfly shaft seals? Carbs that old probably need them.
 
5twins said:
Are you doing butterfly shaft seals? Carbs that old probably need them.
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Yes, for sure. I have the seals already. Waiting for a few parts (butterfly screws) before I pull the shafts out. Also waiting for needle jet orings and mains and pilots.

This bike is supposed to be jetted with 110 mains / 47.5 pilots on the outer cylinders. The Center is supposed to be 107.5 / 47.5. Went to local bike dealer with friends today. Arrived and the salesperson came out and said “that’s my bike”. We couldn’t figure out what he was talking about. Turns out he owned my bike back in 2017!. He told me a lot of the history of the bike and commented when he sold it, it had expansion chambers on it and he re-jetted it really rich. I then thought (as WideAwake commented) maybe that’s why it smokes so much at higher throttle openings. When I opened up the carbs I found some odd jets. 45 pilots and 120 mains for the left and Center cylinders and 110 in the right hand side. Don’t know why someone would have done this.

I’m hoping going back to the stock, leaner jets will yield much better performance.

Stay tuned!
 
Wow, that carb jetting was a mess, lol. I'm surprised you weren't fouling plugs.
 
Plugs were getting on the dark side and a bit oily. Leaning it out should make it run like a scared (750 lb) rabbit.

Up 4 sizes on the mains and down 3 sizes on the pilots. Doesn’t seem to make sense. Hopefully I can achieve a good idle. Before i rebuilt the carbs the best I could do was about 1500, sometimes 1300. Spec is 1000.
 
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Well, I'll bet the CV type carbs helped them not foul. This carb type only gives the motor what it can use. Giving it full throttle doesn't necessarily mean the slides will lift all the way. They'll only go up as much as the bike can use. So, those large mains probably weren't flowing fully.
 
Could be true, but when I got on the throttle you could probably see the smoke cloud from Buffalo..lol.

swapped out the first set of throttle shaft seals. They were as pliable as the new ones. I’m in there anyway do I’ll swap them all to be safe.
 
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Two of three cleaned with new shaft seals; orifices installed to reduce surging. Still waiting for jets and gaskets. Look 100% better. Can’t wait to test it with the proper sized jets in it.

One of my vacuum taps loosened up again. Had previously sealed it with Three Bond. I’m thinking I need to use something more permanent like JB Weld. Recommendations on which type of JB Weld to use or other suggestions.


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bosco659 said:
like JB Weld. Recommendations on which type of JB Weld to use or other suggestions.
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Yes. J B Weld Original. Fixed many a carb with it.
Those carbs are made from Zamak. It's a zinc alloy. It it forms an oxide layer on it when exposed to oxygen.... like, almost immediately. For best adhesion you should scrub it with a metal brush of some sort... and already have the JB mixed and ready to go.... immediately slather the JB on and stick it together.
Maybe a gun bore brush or similar to clean the hole out.
Oh... and don't get any inside the fitting... :sneaky:
 
Jim said:
Yes. J B Weld Original. Fixed many a carb with it.
Those carbs are made from Zamak. It's a zinc alloy. It it forms an oxide layer on it when exposed to oxygen.... like, almost immediately. For best adhesion you should scrub it with a metal brush of some sort... and already have the JB mixed and ready to go.... immediately slather the JB on and stick it together.
Maybe a gun bore brush or similar to clean the hole out.
Oh... and don't get any inside the fitting... :sneaky:
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Ok thanks for the tip. Will have to check to see if I have a wire brush that small.
 
bosco659 said:
Ok thanks for the tip. Will have to check to see if I have a wire brush that small.
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If not, maybe scrape inside the hole with an Exacto knife?
Anything that removes (most of) the oxide layer
 
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