Suzuki 2 Strokes

Dear Suzuki community

Unfortunately I don’t know if the topic has been discussed already. At least I haven’t found it.
I’ve an incomplete T250 and thinking of making a racer for hill climbing. Therefore I was looking around for some samples and I’ve seen that most of the T20/T250 race machines have some rear frame strengthening bars. In a US technical bulletin they even talk about a huge strengthening plate.
What’s your experience there? I don’t have in mind of tuning the engine that much. Is there any big difference and really suggested? If “yes”, do you recommend brazing or welding? What kind of welding?
Thank you very much for your feedback and please excuse my English skills.

Greetings from Switzerland
Roland

Your English is fine. I really can't answer your question, but I'm sure someone here has the knowledge you seek. WELCOME!!!



Lane

Hi Lane

Thanks a lot.
I’m sure that at least there is some know how about frame welding/brazing in this forum. May someone will be able to give an answer/recommendation about their experience there?

Greetings
Roland

Hi Rolland
I am also based in Switzerland I race a TR500 replica and originally I had a T500 frame that was strengthened by adding 2 tubes and welding them in place. I am not sure if I still have pictures but will check. I no longer have the frame as I changed to a Yamaha frame for my bike. However I think you will not need so much strengthening on a 250 frame.

Regards
Eamonn

Hi Eamonn

Thanks for your reply. I'll send you a PM.

Best regards
Roland

Hello Roland,

If you do a Google search for "Suzuki TR 250" you should get a load of images of how the frame was strngthened. Such as this one:


I might be inclined to get your Hill Climber built with a running engine and then develop the chassis if you discover if the std. frame has short comings. By far the biggest factor to going fast is the "Rider", track time and competition experience are worth more than trick frames when you start out.

Good luck

Geoff

Dear Geoff

Thank you very much for your input.

When I was looking at the web I’ve seen a lot of picture of “TR250” machines with a similar modification as shown in the one you posted.
That was the reason I’m asking here. Is there a real problem/great benefit or are most of them doing it because others do or it was common at that time (building a replica)?

I also recognized how the tubes are placed except if they are welded or brazed. There is always the story of weakening the frame if using the wrong welding technology.

One of my next step is painting the frame. Therefore it would be one of the last chance to modify the frame for longer time.
According your feedback my tendency is to leave the frame as it is. You are right. I’m also able to do it afterwards if really needed.

Nevertheless, more inputs are always welcome.

Regards
Roland

For street use, that frame sriffening would make little difference to most riders and Zunspec makes a valid point, but if it were my bike, I would add two side tubes. A frame needs to be stiff enough to stand braking and cornering forces and European style hill climbs which are races up a steep winding public road (closed for the event) are typically all corners and tight and stiffness is good.

The objective is to tie the steering head to the swingarm pivot in a straight line. That makes the steering head stiffer and the swingarm is less likely to twist at the pivot.

Arguably the best way to attach the new tube is with SIFBronze welding. It has a higher strength than the steel tube it is attached to and bronze welding is done at a lower temperature than welding. More common in the US is TIG welding, but if the tubes fit really well, almost any form of welding or braze would work.

Welding tends to cause some distortion as it cools, so tack the tubes in place and then weld them a little at a time moving from side to side. That way the distortion is minimized. A certified welder will probably not need to do that, but for the rest of us it's a good idea. What I did for year was to tack the parts in place and then take the frame to a professional welder to do the real welding.

Good luck with the racing and please post some pictures.

Hello Roland,

I keep it to english here on the forum, Which hill climbs do you intend to attend ?

Eamonn

Dear TZ375

thank you very much for your helpful statement. Let's see what will be my final decision


Dear Eamonnn

The goal would be "Seebodenalp" in August 2017 and "Michaelskreuz", my local mountain, later on. "Michaelskreuz" is not a regularity competition. It's just for fun.

Regards
Roland

Hallo Roland,

Ok I do not know those mountains. I race my bike in the Spanish Classic Championship.
Normally I go to Spain end of February or early March for 2 days of testing if you are interested.

Regards

Eamonn

I have sent email to your private email address.

Eamonn

Dear all

finally done by a professional welder. Many thanks to all.

Roland

Hard to tell with out close up detail pictures but looks good from this distance. Is the frame painted or powder coated? It looks good!

The frame is painted by myself. I had the paint left over from my previous GT500 project.