no low rpm torque - power t500
Moderators: oldjapanesebikes, H2RICK, diamondj, Suzsmokeyallan
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Rocket350
- On the street
- Posts: 19
- Joined: Sun Sep 13, 2015 11:20 am
- Country: N.C. - U.S.A
- Suzuki 2-Strokes: 1972 T500
Re: no low rpm torque - power t500
I swapped carbs to the cylinders but didn't do much since it was idling at 2k and couldn't get to the adjustment screws because they were inboard! I ended up just putting the old stuff back in the left carb minus the needle seat valve and put the clips back in the middle of the needles. I started it and turned the idle up 1/2 turn on the left and 1/2 down on the right carb thinking maybe the idle is low on the left side. I also rechecked points and timing and verified timing with a timing light. I redid a compression test and by the 4th kick left was 120 and right was 124lbs. After a few more kicks left was 125 and right was 128. I don't know if its low but I know different guages give different results. It feels healthy but maybe if compression is low it *could* effect low end. I had a boat that had one cylinder low and had crappy idle until rpms came up and that cylinder would jump up with the rest. I don't know... she runs awesome after 2500 rpms. I did notice I can turn the left air score in all the way while running on that one cylinder and it keeps running. Maybe because I have the idle adjusted too much to keep it idling on that one cylinder. I have not tried that on the right side yet. Anyhow, the idle seams smoother after adjusting both idle screws. Now it's raining so no test ride for now! Thanks again for all the help.
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ConnerVT
- Novice racer
- Posts: 963
- Joined: Wed Jan 18, 2012 8:01 pm
- Country: USA
- Suzuki 2-Strokes: T500R (now), T500M (40 yrs ago)
- Location: North of Albany, NY
Re: no low rpm torque - power t500
swapping the entire carbs wasn't the best of ideas. Swapping just the brass from one to the other will tell you if the issue is with the new carb kit parts. There still could be an issue with the carb bodies, such as a blocked passage. I know you said you cleaned, but there are some really small internal passages which could be partially blocked. Doesn't take much to affect how things run.
My gut says that your compression is fine, that the seals are likely fine, and that minor adjustments to the timing/gap aren't going to fix you. Could be electrical, but still feel that carbs are where you will find your issue.
The good news is that once everything is sorted out, these are really solid motors, and generally don't give people much trouble. It is finding the things that need to be sorted out after 40+ years that can be frustrating.
My gut says that your compression is fine, that the seals are likely fine, and that minor adjustments to the timing/gap aren't going to fix you. Could be electrical, but still feel that carbs are where you will find your issue.
The good news is that once everything is sorted out, these are really solid motors, and generally don't give people much trouble. It is finding the things that need to be sorted out after 40+ years that can be frustrating.
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Coyote
- Moto GP
- Posts: 3404
- Joined: Tue Oct 21, 2008 2:41 pm
- Country: USA
- Suzuki 2-Strokes: GT550x2, GT750, GS1000
- Location: Tulsa, Oklahoma
Re: no low rpm torque - power t500
Plugs gaped at .022. Is that right or am I just used to .028 - .032 for my 550's? Most NGK plugs I buy are good enough right out of the box even though I always check them.
I was born with nothing and still have most of it left.
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1978 GS1000C
1976 GT550 ongoing money pit.
.
1978 GS1000C
1976 GT550 ongoing money pit.
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ConnerVT
- Novice racer
- Posts: 963
- Joined: Wed Jan 18, 2012 8:01 pm
- Country: USA
- Suzuki 2-Strokes: T500R (now), T500M (40 yrs ago)
- Location: North of Albany, NY
Re: no low rpm torque - power t500
Per owners manual:
"... adjust the spark plug gap to 0.016-0.020 in (0.4-0.5 mm) for NGK; 0.024-0.028 in (0.6-0.7 mm) for Nippon Denso by measuring with a thickness gauge."
I usually set at 0.020 in, as that's the only wire gauge I have. But usually right about there out of the box anyway.
"... adjust the spark plug gap to 0.016-0.020 in (0.4-0.5 mm) for NGK; 0.024-0.028 in (0.6-0.7 mm) for Nippon Denso by measuring with a thickness gauge."
I usually set at 0.020 in, as that's the only wire gauge I have. But usually right about there out of the box anyway.
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Rocket350
- On the street
- Posts: 19
- Joined: Sun Sep 13, 2015 11:20 am
- Country: N.C. - U.S.A
- Suzuki 2-Strokes: 1972 T500
Re: no low rpm torque - power t500
Hmmm. Why did I think .020-.024? I looked st the owners manual and repair manual and both say .016-020 (for NGK). Then on pg90 on the repair manual under regapping it says .020-.024. I guess that's where I got the numbers.
In the meantime I'm going to pick up a gallon of carb cleaner and soak my carbs overnight. Its going to be so much fun taking them off and apart... again. The most joy is the rubber intake boot that I absolutely hate with a passion. I refuse to get the pods. I need to get a new boot.
In the meantime I'm going to pick up a gallon of carb cleaner and soak my carbs overnight. Its going to be so much fun taking them off and apart... again. The most joy is the rubber intake boot that I absolutely hate with a passion. I refuse to get the pods. I need to get a new boot.
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Coyote
- Moto GP
- Posts: 3404
- Joined: Tue Oct 21, 2008 2:41 pm
- Country: USA
- Suzuki 2-Strokes: GT550x2, GT750, GS1000
- Location: Tulsa, Oklahoma
Re: no low rpm torque - power t500
Be sure to remove ALL rubber parts. Carb cleaner plays hell on rubber. Swells like there's no tomorrow.In the meantime I'm going to pick up a gallon of carb cleaner and soak my carbs overnight
I was born with nothing and still have most of it left.
.
1978 GS1000C
1976 GT550 ongoing money pit.
.
1978 GS1000C
1976 GT550 ongoing money pit.
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ConnerVT
- Novice racer
- Posts: 963
- Joined: Wed Jan 18, 2012 8:01 pm
- Country: USA
- Suzuki 2-Strokes: T500R (now), T500M (40 yrs ago)
- Location: North of Albany, NY
Re: no low rpm torque - power t500
Not many rubber bits in a Mikuni VM slide carb - The choke plunger and the top to body gasket.
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Rocket350
- On the street
- Posts: 19
- Joined: Sun Sep 13, 2015 11:20 am
- Country: N.C. - U.S.A
- Suzuki 2-Strokes: 1972 T500
Re: no low rpm torque - power t500
Yup...
So I looked up plugs and they are no longer available as you all know. I remember getting them 20 yes ago! When I went to the parts store and gave them the b-77hc number they gave me autolites. Looking at the service manual the Nippon denso plugs have a bigger gap. Maybe, just maybe I have crap autolites gapped to NGKs and that could be giving me problems at low end? I'll get the b7hs plugs and see what happens. I've never really encountered an engine that was fussy with plugs so I'm doubtful my theory is any good. I didn't make it to the parts store today for carb cleaner. Ugh... I'm avoiding removing the air cleaner boot.
So I looked up plugs and they are no longer available as you all know. I remember getting them 20 yes ago! When I went to the parts store and gave them the b-77hc number they gave me autolites. Looking at the service manual the Nippon denso plugs have a bigger gap. Maybe, just maybe I have crap autolites gapped to NGKs and that could be giving me problems at low end? I'll get the b7hs plugs and see what happens. I've never really encountered an engine that was fussy with plugs so I'm doubtful my theory is any good. I didn't make it to the parts store today for carb cleaner. Ugh... I'm avoiding removing the air cleaner boot.
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ConnerVT
- Novice racer
- Posts: 963
- Joined: Wed Jan 18, 2012 8:01 pm
- Country: USA
- Suzuki 2-Strokes: T500R (now), T500M (40 yrs ago)
- Location: North of Albany, NY
Re: no low rpm torque - power t500
I found it easier to pull the seat, then the batter box, then remove the air box and boot together as a unit. this way, there is tons of room to work. real easy to mount the carbs, as well as check the syncro of the slides. I have been able to pull carbs, rejet, and reassemble in about an hour.
