Recent Posts

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350 Talk / Re: Bridgestone 350 engines required
« Last post by bert Lilley on September 09, 2023, 05:13:26 PM »
Hi vinny,well im talking to a guy in the states who is building a 175 street races yup hes going for it.
I remember you had parts you wished to sell for your175 racers. Do you have anything left from that lot ?.
How are your fleet of 200cc racers doing have you found any more power out of the rascals ?
I was thinging of putting together a 175 to competent my BS350 i have enging cases bored out cylinders ready for T6 alum. Liners etc. But stalled when i read the rules of only22mm cabs. BUT have found away around the ARHMA restrection and and waiting confirmation from a engineering source. So ill hang on for a little while .
Interested to see how your bike are doing
Best Bert
175 & 200 Talk / Re: Crankshaft center seal
« Last post by Joe on September 02, 2023, 06:12:21 AM »
Thanks for the information! I do have a replacement center seal. I have applied for a bonded title for my DT and the dmv reply is in the mail. If it’s approved the bike will be professionally restored (Mechanically) next year. If it’s denied I will sell it and hope to find a running, titled bike. In the meantime I have my recently acquired HS to zip around the county.
175 & 200 Talk / Re: Crankshaft center seal
« Last post by CL-100 on September 01, 2023, 10:34:45 AM »
I bought an early model 175 engine (engine only) and when I received it I was delighted with how well the engine/crank turned over.  Once I had it disassembled I found that the crank center seal was trashed.  The spring around the lip had broken in two.  It took me a while to find the correct seal for my engine as it looks as though the earlier models used a couple of different setups for the center bearing and seals.  I ended up sending the crank with new bearings and seals to Northern Crankshaft for replacement of the parts and correct reassembly.  They rebuild a lot of two-stroke crankshafts, mostly for snow-mobiles, and have always done a good job for me. 
175 & 200 Talk / Re: Crankshaft center seal
« Last post by czmike on August 31, 2023, 08:46:52 PM »

Hi Joe,

Age, mileage, extreme heat & cold are the main things that degrade any rubber/plastic lip-type seal.

I am in the middle of replacing the centre seal & bearing on my 175HS crankshaft.
I was hopeful of this being unnecessary but on close inspection of the centre seal, which you can do in-place, it had radial cracks in its sides.
My bike has only traveled 3,000 miles and has not been ridden since 1972.
The good condition of the bike and the engine confirmed the low miles and that it had been stored carefully under good conditions.
Nonetheless one main bearing was rusted solid (drive side) and the seals all need replacing including the crank centre seal.
I am replacing all main bearings and the centre bearing as well while it is apart.
I suspect your centre crank seal will be due for replacement as surely would all others that have never been replaced.
You could perform a pressure test on the motor to measure the seal leakage but I think you can safely assume it leaks.
None of this you want to hear of course but it is quite typical and well, just that thing called reality.

If your engine is not stuck and runs OK then you might consider continuing to use it. I wouldn't use it hard though (which is surely the way you would want to use it!).
If you have difficulty starting it, particularly when hot this could be an indication of crank seal problems.
Other users might be able to advise what are the tell-tale signs of a leaking centre seal.
Any running or tuning problems will probably be mystifying until you replace all the seals.

Best Regards,
175 & 200 Talk / Crankshaft center seal
« Last post by Joe on August 31, 2023, 02:45:49 PM »
Can someone school me on the crankshaft center seal ? Does it go because of age, mileage, abuse, all of the above? My DT sat for years . Any chance it will be ok ? Thanks !
175 & 200 Talk / Re: Gas left on. Can it get into engine?
« Last post by Joe on August 28, 2023, 06:27:15 AM »
Thanks !
SR Racer Talk / Re: SR175 ports
« Last post by SR-175 on August 27, 2023, 04:34:27 AM »
Hi Dave,

In the downloads section of the site you will find - "Tuning Up For Competition" - This might help with the details you are looking for.

175 & 200 Talk / Re: Gas left on. Can it get into engine?
« Last post by OldSwartout on August 25, 2023, 08:32:44 AM »
It could only get into the crankcase, not the transmission. If you were concerned about it (possible hydraulic lock causing damage to the piston/rod), you could pull the plugs and kick it over rapidly a few times (with the ignition off). Any excess fuel in the crankcase would blow out the plug holes or into the exhaust.  You would want to let everything dry off before trying to start it.
175 & 200 Talk / Gas left on. Can it get into engine?
« Last post by Joe on August 24, 2023, 11:53:23 AM »
Sooooooo, yesterday I find I left the petcock on and lost about a half gallon that looks like dripped down from a loose petcock connection thence to my garage floor. Got me to thinking what happens if the float valve doesn’t seal ? Can it get into the engine cases ? Should I drain mine ? Happened to me once on a Yamaha 650 when the vacuum actuated petcock let loose and gas got in the cases.
SR Racer Talk / SR175 ports
« Last post by dcX on August 23, 2023, 04:47:35 PM »
Are the inlets & exhaust ports the same (or different) on the SR175 compared to a DT175.

I'm getting my DT cylinders relined (cast iron liners) so have the opportunity to have the port layout I want, if the SR175 ports are different (more power) then I'll go down that route. With the caveat that someone will kindly share port details: photos / dimensions / layout / diagram.

Many thanks
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