Hello from new member with a T20

[gammakeith]

Hi,

I'm based in Nottingham UK and have just bought a nice little T20 at a Bonhams auction (see attached). The idea is to check it over over the winter so its ready for my wife to ride when/if she passes her test (she is currently riding a H100 Honda). I'm not unfamiliar with Suzukis as I have done full rebuilds on a GT750 and on the RG500 I have at present. I love 2 strokes and also have a 1948 Scott Flying Squirrel, 1951 Cyclemaster, 1985 Suzuki RG500 and a1999 Honda CRM250AR. However, I have little knowledge about the "T" bikes so any tips on what to check would be appreciated as this looks to be a good site for them.

I am starting with no history other than it was imported from Ohio in 2019 showing 8506 miles. Its only showing 8,533 now which is not a good sign so I will write to the PO to see if I can get any information. The mileage may be genuine as it looks to have been stored for a long time as the frame paint looks original and is not too bad. It starts, runs and sounds mechanically quiet on choke but dies as soon as the throttle is opened but that could just be bad fuel or clogged carbs. I'll test primary compression shortly and see if I can use/modify the leakdown tester I made for my CRM250 to check the crank seals. I'll likely pull the barrels to check the top end and am a bit unsure if I should strip the whole engine as a precaution? The wiring is a bit dodgy in places and the rear shocks have absolutely no damping. It also looks like the drive chain made a bid for freedom at some point as there is a well done welded repair above the front sprocket. Other than that it looks pretty good!

Best wishes,

Keith

[Evans Ward]

Welcome Pretty bike! A thorough carb cleaning totally disassembled in an ultrasonic would be what I’d try first. Check jets and only use genuine Mikuni if any are needed. Avoid the generic kits but you probably already know that. You have a great stable of smokers- would love to see that Scott Flying Squirrel in another post!

[Alan H]

Welcome to the madhouse, Keith.

[gammakeith]

Thank you for the welcome. I've just had another quick look at it and spotted a couple of more things. The small cover (clutch adjuster I think) under the engine is cracked and damaged. Its oozing both gearbox and 2T oil underneath and it appears that the crankcases have been put together without the 2 small bots at the front (or perhaps they have been overtightened and fallen out). The cylinder barrel to crankcase joints are also oozing sealant. Thus, its looking more and more that stripping and inspect the engine properly will be the best way forwards.

Keith

[dollydog]

i'm based in ilkeston, so not far away although i primarily rebuild t250/gt250 engines [ramair]. i've also done a 1966 t10, an rg250, ts250, plus my own specials like the gt285, the gt350, gt250 reed valve and the gt250 big bang. the super 6 is one engine i've never done, but hey, how hard can it be? if you need any help just shout
cheers, dd.
p.s. i also refurb mikuni vm carbs

[gammakeith]

Cheers Dollydog. Its good to know that you are not far away. I have a decent lathe so could make the seal/bearing carriers so I could run smaller seals and bearings which appears to be required for the T20 as originals are nla. However, I do not have a hydraulic press and have never done a pressed together crank before so that part is beyond me. The rest of it doesn't worry me

Keith

[daxman]

Keith afaik there's a crank rebuilder very close to Nottingham (Kegworth way I think).. I'm sure others here will verify that and recommend accordingly

[gammakeith]

Cheers. I am aware of SEP at Kegworth though I have never personally used them. I sent them an email to see if they could help but got no response. Maybe a phone call will have better luck?

Keith

[Alan H]

Best of luck there. Do a search for sep in the quick links top left of the screen.
Grampian is better, or Chris Applebee.

[daxman]

Thoughts about PJME?

[gammakeith]

I made up some adapters for my leak tester on the lathe but failed to get any pressure whatsoever on either side. The right side base gasket was blowing really bad and I couldn't really tell where air was escaping on the other side as it seemed to be coming from all over. At that point I gave up and stripped the top end. A combination of nearly loose head bolts, reused base gaskets bodged with silicone and undressed bumps where the barrels were previously separated with a hammer and screwdriver conspired to make any kind of meaningful lower barrel seal impossible. The pistons and rings look reasonably OK and the bores just look like they need a light hone which accounts for why I got a respectable 145 and 150 psi on a simple compression test. Its been rebored to +0.5mm and something clearly went pop on the left cylinder at some point as the head is peppered. The big one, however, is the near 1mm of play in the left hand big end so a crank rebuild is definitely needed. I think a previous owner spotted that and hastily put the engine back together to sell. I don't think it was the last owner as he did 30 or so miles and actually went to the trouble to get an MOT on it even though it is not needed any more. I guess it ran like a complete bag of spanners when he rode it so he auctioned it to get rid.

Whoever, put that engine together should have all of their spanners shoved where the sun doesn't shine and barred from touching a motorbike engine ever again.

Keith

[dollydog]

definitely not me keith as i said, i've never rebuilt a super 6 engine. if i had photo's of some of the 'rebuilt' engines i've had to rebuild again, you'd be amazed at some of the complete numptys there are out there calling themselves mechanics. i presume when you said 1mm play in the big end you meant up and down movement? side to side the book reckons up to 3mm, although i'd do them long before they got that bad. i had an engine off a proddy racer in yorkshire somewhere, who sold me his spare engine that had just been rebuilt by a professional and had lasted about five minutes before it started 'making funny noises'. hardly surprising, the shop had put the right crankpin the wrong way round. so instead of the hole in it next to the oil thrower, it was on the other end. would have been fine if it was a gt250a engine, but it was a ramair
cheers, dd.
p.s. then there was the m6 nut lying in the bottom of the gearbox in another engine. oh yes, the one that somebody had nearly straightened out a bent conrod with a pair of stillys - you could see the teethmarks in it. i could easily fill a page with examples. anyway, best of luck with the super 6

[gammakeith]

Well, that's the engine stripped now. Cracking the cases did not reveal any real horrors as I had feared. No cracks or damage to the locating pegs. The upper case has one snapped off thread that someone has tried to drill out and wandered off to one side and one thread housing that has burst out due to a longer bolt being used.

As expected, the crank is not good. As noted previously, the left had big end has nearly 1mm up/down play and the right has a noticeable knock. Both outer mains are rumbly with play on one side and the inner seals feel very slack on the shaft so were probably leaking. The left side crank also has a nice groove down just inboard from the alternator taper it which will need a sleeve or welded repair. The inner main bearing feels good after a good wash so that can be reused at least. Interestingly, the outer seals are good and look to have been replaced fairly recently. Smaller seals have been fitted running in custom housings.

Unfortunately, those outer bearings look to be nla as classicsuzukiparts.nl lists all the seals as being available but not those outer mains. They are 55x20x15 and with a locating groove, peg hole and a chamfer on one side. I just rung SEP up and the guy I spoke was completely confident they can work around any parts issues so I'll save up my Christmas money and take it to them in the New Year.

The gearbox etc all looks lovely so it could have been worse!

Keith

[daxman]

I think a previous owner spotted that and hastily put the engine back together to sell. I don't think it was the last owner as he did 30 or so miles and actually went to the trouble to get an MOT on it even though it is not needed any more. I guess it ran like a complete bag of spanners when he rode it so he auctioned it to get rid.

Whoever, put that engine together should have all of their spanners shoved where the sun doesn't shine and barred from touching a motorbike engine ever again.

Keith

That's some poor luck. Sounds though like its now found a committed owner. All the best for teh engine rebuild.

[gammakeith]

Well its all back together again and sounding good. I went with SEP for the crank rebuild in the end as they are reasonably local. The bores just needed a hone but the pistons and rings were worn so I put in a pair of pattern GT250/X7 pistons that are a reasonably good match and have been used by quite a few with good results. The oil pump was rebuilt with new seals and new tygon oil lines as the old system was a mess. I think I solved the mystery of why the engine was put together so messily It was very odd as the outer crank seals were nearly new and the pistons had almost no carbon. You surely wouldn't go to the hassle of making up custom seal carriers and ignore an obviously failed big end would you? The clue came with an oil tank drain bowl that was half full of some strange gritty stuff (see picture). Looking inside the drained tank with a torch revealed lots of shiny sparkles in the residual oil and the penny dropped. The oil tank had been shot blasted prior to a repaint and clearly had not been rinsed out afterwards. I would imagine that caused the rapid big end failure. Perhaps the source for the horrid noise was investigated and the engine put back together quickly and shoddily to sell on quickly.

Lots of other jobs done including adding indicators, wiring repairs, headstock bearings, forks rebuilt and swinging arm converted to needle rollers. In contrast to the rest of the bike the wheels and brakes needed no attention. Oh well, the bike may not look much different but it should run reliably for a while now and its given me something to do during this (hopefully) final lockdown.

https://youtu.be/TEEsZhYXGX0

Keith