gt250/gt500 oil pump question

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dollydog
Yeah Man, the Interstate
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Suzuki 2-Strokes: several gt250 ramairs

gt250/gt500 oil pump question

Post by dollydog »

are there any designation markings on the 500 pump? i've got a few oil pumps and just wondered if there was a 500 in there. gt250 pump just says iso on it and made in japan so that's not much use. there is 3.9 stamped on top of the bolt that holds the shaft in, but that's it ???
cheers, dd.
ps, was going to use the 500 pump for the 350 :)
GTS250 road registered. TS250 engine, Ramair frame.
GT250 big bang road registered. Both pistons fire the same time. USD forks.
GT285 road registered. Overbored - 58mm and TS125 +2 pistons fitted.
GT10 road registered. '65 T10 engine, GT250 frame.
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jabcb
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Re: gt250/gt500 oil pump question

Post by jabcb »

The T250/GT250, T350 & T500/GT500 oil pumps have different flow rates.
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dollydog
Yeah Man, the Interstate
Posts: 513
Joined: Fri Aug 11, 2017 7:09 am
Country: england
Suzuki 2-Strokes: several gt250 ramairs

Re: gt250/gt500 oil pump question

Post by dollydog »

hi jab, i know that bit :D but how can you tell the difference without trying them? which was my original question :)
cheers, dd.
GTS250 road registered. TS250 engine, Ramair frame.
GT250 big bang road registered. Both pistons fire the same time. USD forks.
GT285 road registered. Overbored - 58mm and TS125 +2 pistons fitted.
GT10 road registered. '65 T10 engine, GT250 frame.
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dorT500
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Suzuki 2-Strokes: '75 T500M since '93 Ridden it over 100,000 mi
Location: Galveston County, Tx.

Re: gt250/gt500 oil pump question

Post by dorT500 »

Hey dollydog, under the Google 'Images' tab enter T/GT 500 pump and then T/GT250 pump. From a brief search I made, it appears the pump levers are slightly different. Other than that, yes, my T500 spare oil pumps all have the '3.9' stamped on the reverse thread plunger guide screw. I might add some pics here shortly.

Edit....one pic of a pump (more to come) but even more interesting to me is the vacuum fuel petcock mod... http://teamghettoracing.com/bikes/road/ ... and-carby/" onclick="window.open(this.href);return false;
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dollydog
Yeah Man, the Interstate
Posts: 513
Joined: Fri Aug 11, 2017 7:09 am
Country: england
Suzuki 2-Strokes: several gt250 ramairs

Re: gt250/gt500 oil pump question

Post by dollydog »

thanks for that chuck :D the levers were the only difference i could see, so according to that a longer lever at a certain throttle position would give more oil? sounds daft though :D have you got a t500 pump you could strip down and we'll compare the sizes of the various parts, 250 against 500? i reckon suzuki are trying to pull a fast one :D
cheers, dd.
GTS250 road registered. TS250 engine, Ramair frame.
GT250 big bang road registered. Both pistons fire the same time. USD forks.
GT285 road registered. Overbored - 58mm and TS125 +2 pistons fitted.
GT10 road registered. '65 T10 engine, GT250 frame.
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dorT500
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Posts: 253
Joined: Mon Jun 12, 2017 12:01 pm
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Suzuki 2-Strokes: '75 T500M since '93 Ridden it over 100,000 mi
Location: Galveston County, Tx.

Re: gt250/gt500 oil pump question

Post by dorT500 »

dollydog wrote:........... have you got a t500 pump you could strip down......
Uhh... Yes. :)
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GT250 Image
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I've been meaning to strip down at least one of these again anyway to hopefully confirm my thoughts back when, that excess smoking (2T) cannot be exclusively blamed on banjo check valves, wrong adjustment, etc., that is, my thinking a few years ago was that a worn rotating plunger shaft and of course its bore could cause excess oil to bypass around and be discharged with the rest of the metered oil. Pumps out there that in the vast past that have been run dry for some period of time or even worse, have been disconnected from the oil tank and left still bolted on by some that would choose to run pre-mix. Thus increasing the population in the wreckers/salvage yards, though..... ironically.... increasing bike parts availability for us vintage enthusiasts. My theory on this could be wrong....I don't think so...it's just I believe that was my thinking when I last had one apart several years ago. I just need to look inside at the 'works' of one of the pumps again.


Note...it appears to me the reverse thread screw is being shown screwed in the wrong direction but otherwise pretty neat little clip..
https://www.youtube.com/watch?v=1x5Dau9N9cg" onclick="window.open(this.href);return false;"

From what I can remember, each of my spares (at least two previosly used by me) had some kind of issue, save one, that I might not have tested yet.

I can remember many years back on this forum and others that the general consensus was that you should not take one of these pumps apart....that they were not meant to taken apart. Way back when, the idea was to replace them with new ones when they did not meet the discharge rates supplied to the service departments of Suzuki dealerships. I seem to recall that warning is even in one of my service manuals? ............another indication from the manufacturer that just plain wear over the years in these pumps can make them NOT "bullet proof" as many have described over the years?

I'll try and get a chance in the next couple of days to take one apart as you requested.
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dollydog
Yeah Man, the Interstate
Posts: 513
Joined: Fri Aug 11, 2017 7:09 am
Country: england
Suzuki 2-Strokes: several gt250 ramairs

Re: gt250/gt500 oil pump question

Post by dollydog »

good man :D i've got a definite 250 oil pump already partially stripped down, so i'll get the digital measuring thingy out and start measuring a few bits up. i'm going to peruse your photo's again and see if i can spot any glaring difference :D thanks again.
cheers, dd.
GTS250 road registered. TS250 engine, Ramair frame.
GT250 big bang road registered. Both pistons fire the same time. USD forks.
GT285 road registered. Overbored - 58mm and TS125 +2 pistons fitted.
GT10 road registered. '65 T10 engine, GT250 frame.
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dorT500
To the on ramp
Posts: 253
Joined: Mon Jun 12, 2017 12:01 pm
Country: USA
Suzuki 2-Strokes: '75 T500M since '93 Ridden it over 100,000 mi
Location: Galveston County, Tx.

Re: gt250/gt500 oil pump question

Post by dorT500 »

I would not bet $1000.00 that they are exactly alike except for the lever but I would bet......well....I would bet less :wink: that they are the same.
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dollydog
Yeah Man, the Interstate
Posts: 513
Joined: Fri Aug 11, 2017 7:09 am
Country: england
Suzuki 2-Strokes: several gt250 ramairs

Re: gt250/gt500 oil pump question

Post by dollydog »

one thing i did notice was after taking the triangle off the end, there was a cam inside. i wonder if that's a different size? it's a bit difficult to measure without knocking the holding pin out and taking the [lever] shaft out, but there's a reason for a cam of a certain size, yes? atm, that's my bet. can you get a photo of the pump, end on with the triangle removed? just a visual might give us a clue :D
cheers, dd.
GTS250 road registered. TS250 engine, Ramair frame.
GT250 big bang road registered. Both pistons fire the same time. USD forks.
GT285 road registered. Overbored - 58mm and TS125 +2 pistons fitted.
GT10 road registered. '65 T10 engine, GT250 frame.
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dorT500
To the on ramp
Posts: 253
Joined: Mon Jun 12, 2017 12:01 pm
Country: USA
Suzuki 2-Strokes: '75 T500M since '93 Ridden it over 100,000 mi
Location: Galveston County, Tx.

Re: gt250/gt500 oil pump question

Post by dorT500 »

dollydog wrote:...... but there's a reason for a cam of a certain size, yes? atm, that's my bet. can you get a photo of the pump, end on with the triangle removed? just a visual might give us a clue ....
aahhhh....you may be on to something there.

More pics coming but here is a start. High points of cam..

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Measured while still in....bumping pinned shaft collar.
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Edit..additional pics

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aahhh. this was one I had to put heli-coil inserts into. I think I had to cut off at least one winding at the top of the insert so it wouldn't block the tiny oil port at the bottom. Didn't even need to break off the inserts tangs the way it worked out.

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______________________
_______________________________
GONE.......WITH A PUFF OF SMOKE AND A BLUR OF SPOKE
dollydog
Yeah Man, the Interstate
Posts: 513
Joined: Fri Aug 11, 2017 7:09 am
Country: england
Suzuki 2-Strokes: several gt250 ramairs

Re: gt250/gt500 oil pump question

Post by dollydog »

hmm, thanks for them chuck :D most things on mine measure up, but that cam lobe looks far bigger, and unless you've got an exceptionally thin metal rule, then the end aperture is far bigger. i can't get my metal rule in there at all. the 3 holes on the end are 25mm centre to centre, except one which is 27mm ditto and uses 3 x m4 screws. aperture at its widest is 18mm and narrowest 15mm. but that cam definitely looks bigger - way bigger :D
cheers, dd.
GTS250 road registered. TS250 engine, Ramair frame.
GT250 big bang road registered. Both pistons fire the same time. USD forks.
GT285 road registered. Overbored - 58mm and TS125 +2 pistons fitted.
GT10 road registered. '65 T10 engine, GT250 frame.
User avatar
dorT500
To the on ramp
Posts: 253
Joined: Mon Jun 12, 2017 12:01 pm
Country: USA
Suzuki 2-Strokes: '75 T500M since '93 Ridden it over 100,000 mi
Location: Galveston County, Tx.

Re: gt250/gt500 oil pump question

Post by dorT500 »

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dorT500
To the on ramp
Posts: 253
Joined: Mon Jun 12, 2017 12:01 pm
Country: USA
Suzuki 2-Strokes: '75 T500M since '93 Ridden it over 100,000 mi
Location: Galveston County, Tx.

Re: gt250/gt500 oil pump question

Post by dorT500 »

dollydog wrote:........... the 3 holes on the end are 25mm centre to centre, except one which is 27mm ditto and uses 3 x m4 screws. aperture at its widest is 18mm and narrowest 15mm.
I'll get those for you also.
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dorT500
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Posts: 253
Joined: Mon Jun 12, 2017 12:01 pm
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Suzuki 2-Strokes: '75 T500M since '93 Ridden it over 100,000 mi
Location: Galveston County, Tx.

Re: gt250/gt500 oil pump question

Post by dorT500 »

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GONE.......WITH A PUFF OF SMOKE AND A BLUR OF SPOKE
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dorT500
To the on ramp
Posts: 253
Joined: Mon Jun 12, 2017 12:01 pm
Country: USA
Suzuki 2-Strokes: '75 T500M since '93 Ridden it over 100,000 mi
Location: Galveston County, Tx.

Re: gt250/gt500 oil pump question

Post by dorT500 »

Been kind of rushed lately and have not even run a rag through this spare to see if that is dirt or what. :shock:
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I wonder if the '49' is just a inspectors stamp , lot number, or a designation number? I dunno..
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