Cylinder thread damaged

Need some help? Put your question up here. Many years of experience on the board to help you get up and running.

Moderators: oldjapanesebikes, H2RICK, diamondj, Suzsmokeyallan

Post Reply
njdmoto
Still in the Driveway
Posts: 3
Joined: Wed Jul 19, 2017 4:08 am
Country: Australia
Suzuki 2-Strokes: Katana 250, t250 hustler

Cylinder thread damaged

Post by njdmoto »

Hi All,

I'm working on the restoration of a T250 and I'm looking for a solution to the stripped outside thread on the cylinder. When I don't use an exhaust gasket I can get a little bit of bite on the thread when attaching the exhausts, but that's not a long term solution.

Perhaps I have been searching using the wrong terminology but I can't find anything in the forums.

Any suggestions?

Thanks
Neil
You do not have the required permissions to view the files attached to this post.
rngdng
AMA Superbike
Posts: 1769
Joined: Tue Oct 14, 2008 6:47 pm
Location: Blythewood, SC, USA

Re: Cylinder thread damaged

Post by rngdng »

Man, I don't know. I might take it to a machinist for advice.
If you stroke it more than twice; you're playing with it.

Too many bikes, too much time, ENOUGH SPACE, FINALLY! Never enough money.........
User avatar
jabcb
Moto GP
Posts: 4240
Joined: Mon Dec 13, 2010 4:32 pm
Country: USA
Suzuki 2-Strokes: 69 T350 thru 75 GT750
Location: southwestern Pennsylvania

Re: Cylinder thread damaged

Post by jabcb »

A thread chaser might restore the threads to the point its workable again. A universal tool isn’t too expensive, but I would take the part to a shop that has experience with the tool.
Here is a video: https://www.youtube.com/watch?v=s9tAVV1EfN4
BAS (Bike Acquisition Syndrome) - too many bikes but have room for more

Suzuki:
GT750 2x75
GT550 72 & 75
GT380 72
T500 69 project & 73 project
T350 69 & 71
Honda 85 CB650SC & 86 CB700SC
09 Triumph Bonneville SE
User avatar
Alan H
Moto GP
Posts: 3160
Joined: Thu Feb 16, 2012 11:50 am
Country: England
Suzuki 2-Strokes: 4 x GT550s - J, M, A, B.
Location: The Republic of South Yorkshire

Re: Cylinder thread damaged

Post by Alan H »

Aluminium tape round the threads.
Think of how stupid the average person is, then realise that half of them are more stupid than that.
njdmoto
Still in the Driveway
Posts: 3
Joined: Wed Jul 19, 2017 4:08 am
Country: Australia
Suzuki 2-Strokes: Katana 250, t250 hustler

Re: Cylinder thread damaged

Post by njdmoto »

jabcb and Alan good suggestions!

I might try both. Get the thread cleaned up as much a possible, then a bit of tape.

Many thanks
Vintageman
Expert racer
Posts: 1483
Joined: Tue May 18, 2010 5:38 pm
Country: USA
Suzuki 2-Strokes: Suz, Yam, Honda, Kaw.
Location: New Hampshire

Re: Cylinder thread damaged

Post by Vintageman »

I think its 48x1.5 thread if that fyi helps
Current Bikes
74 GT250 (T350 upgrade),
76 GT250 (T350 upgrade),
71 T350,
70 T350,
74 GT380,
75 T500,
73 GT550,
75 GT750,
72 Yamaha DS7 (R5 upgrade),
77 Yamaha RD400 (Daytona Cyls),
willdesign
Still in the Driveway
Posts: 1
Joined: Fri Aug 18, 2017 8:20 pm
Country: New Zealand
Suzuki 2-Strokes: T350, Guzzi Eldorado, R80/7

Re: Cylinder thread damaged

Post by willdesign »

njdmoto did aluminium tape work?
I've same problem. '71 T350.
Have talked to 2 machinists experienced with bikes & cars and both said it'd be over a day's labour for them: not economical.
Be glad to hear how you got on
njdmoto
Still in the Driveway
Posts: 3
Joined: Wed Jul 19, 2017 4:08 am
Country: Australia
Suzuki 2-Strokes: Katana 250, t250 hustler

Re: Cylinder thread damaged

Post by njdmoto »

willdesign,

I have just received the thread chaser, so ill let you know how It all goes.
rngdng
AMA Superbike
Posts: 1769
Joined: Tue Oct 14, 2008 6:47 pm
Location: Blythewood, SC, USA

Re: Cylinder thread damaged

Post by rngdng »

njdmoto wrote:willdesign,

I have just received the thread chaser, so ill let you know how It all goes.

If it doesn't work...fill the threads with JBWeld and rework the threads. I know it sounds crazy, but I did an experiment once where I drilled out an exhaust stud to 1/2" and filled it with JBWeld. After drying for a couple of days I tapped it to 8mm and put a long bolt into the hole. I tightened the bolt (using a torque wrench) and at 20 ft/lbs the bolt broke off. The threads held...



Lane
If you stroke it more than twice; you're playing with it.

Too many bikes, too much time, ENOUGH SPACE, FINALLY! Never enough money.........
Post Reply