Differences in BS 350 performance?

[Richard Clark BS parts]

Has anyone else noticed differences in 350 performance?

My perspective comes from owning many 350 GTR's, with very few GTO's

I have owned perhaps 100 GTR's through the years, from new ones to old junk.


Had around 25 good runners, all of these ran well.  But, the differences were great. about
a third were average, nice overall machines.


One third were turds, ran well but just plainly slow.
None of these seems to have any problems, just did not perform very good.
Ran well, started well, operated well, but seems to be missing something?  Sounded OK however.


The other third were real performers, just screamed and seemed to have 10 more horsepower.
Sounded somewhat different, perhaps a bit ragged, but did they run!!  These are the bikes
that seemed to have started the reputation for the GTR being such a beast of a 350.


Keep in mind some of these machine I have a talked about were new or almost new, not old bikes that
needing everything.

Anyone else noticed anything like this?



Questions? or need Bridgestone parts? call:

Richard Clark
812-944-1643  8am-6pm EST Weekdays

[Dave K]

I didn't have that many different Bridgestones to compare, but I do remember the '69-'71 500 Kawasaki's. Same story as you talked of. Some were rockets and they were bone stock. Some just ran fine, but the performance wasn't there. As I am sure, there was some sort of "glitch" in them that caused this. A friend had a Kaw 900 LTD. It was a turd. It has been slowly passed around this area since he bought it new in '76. About 10yrs. ago, a new owner dug into it and the timing marks were not stamped correctly. All of a sudden, this bike came alive from her sleep, once set up correctly.

[Bridgestone Man]

I too have noticed differences in performance between my three 350 stones.  One is really
fast ( my rider, wonder why?)  and the other two, which seem about the same buy a lot slower.

Sam Keys

[rocketman]

 Thanks for making me think again Richard! I'm sure this list of speculative causes is going to grow to be extensive. Ignition timing surely a factor. Just because it was set at the factory...  Also,internal clearances are going to be a factor. Early/late crankshaft and seal designs,early design end seals mentioned in service letters added friction. Poor oiling or too much oil injected will both cause differences. Clutch hub was changed to a lightweight aluminum component at some point,replacing the heavier cast iron original design. This has to allow you to access a bit quicker whatever horsepower you have,less weight to spin. Any slight diff in the rotary valve timing would make a difference. Bikes that need to charge harder for whatever electrical component issue will swallow more horses. Castings like cylinders and cases may have varying degrees of roughness or material that should have been cleared away before assembly,causing flow differences. Port matching,some engine assemblies will just have a closer match between ported castings and gaskets than others,flow again. Other stuff? You bet!  Mark.

[Toystoretom]

I've only got one "runner" but it seems to do alright. At about 5 grand it seems to come on the ports in a big way. Right now I'm just happy it runs.

You never know, maybe mine is one of the "slow" ones and I'll be able to get a bunch more out of it 

[OldSwartout]

I too have noticed differences in performance between my three 350 stones.  One is really
fast ( my rider, wonder why?)  and the other two, which seem about the same buy a lot slower.

Sam Keys

It would be an interesting exercise to sort this out:
1. Run the fast one and one of the slower ones against each other on an open stretch of highway with similar size riders to see if there really is a significant difference.  Sound and vibration can make a big difference in perception.
2. Check timing with a dial indicator, not the crank pin notch.
3. Swap exhaust pipes. Plugged internal openings or differences in internal baffle position could be the difference in performance.
4. Compare rotary valve opening & closing timing.  These could be different, transfer and exhaust ports are surely the same, although if no differences are found to this point, that is something to check.

[Richard Clark BS parts]

I have looked  at new 350 cylinders and there is much differences to size and quality of the ports, some are nice
and smooth, while others have rough casting material all over them

I suppose this is one big difference.



Questions? or need Bridgestone parts? call:

Richard Clark
812-944-1643  8am-6pm EST Weekdays

[rocketman]

 Karl,I agree 100% re:timing with a dial vs.using the crank notch. I also like the good old manual feel of sliding a slip of rice paper through the contacts instead of using a light. I know from the old Kawasaki shop days,that the tech. who does the pre-sell prep work makes a difference too. How thoroughly were all the factory settings and adjustments checked? Carb sync and even sort of back to basics,are the cables adjusted so the throttle slides are both completely open? And I see I made you think a little too,Richard. It's contageous isn't it? Great stuff.  Thanks,Mark.

[reed]

When I worked with new motorcycles like Kawasakis there were differences in COMPRESSION and CRANKCASE LEAKS.
So an important factor in maintaining the correct air- fuel mixture in a 2- stroke engine is a crankcase that is air tight.
I would do a crankcase pressure test block off the exhaust port take off the carbs block off the intake port put air
into the cylinder at about between 8 and 10 PSI and listen closely for escaping air.The maximum leakage is 1 PSI per
Minute so i would inspect head gasket base intake manifold crankcase seals and crankcase halves so even if the
motorcycle had no miles on it the crankshaft seals were leaking.So there a differences in performance!
Crankcase seals were over looked because the engine was new.
Carbs needle jet and needle to control a proper air - fuel mixture ratio and between 1/4 and 3/4 openings i would check
the needle jet and needle for being worn even new carbs and replace with new this works with old carbs brings them
back to life!So check timing rotary valves ports and exhausts even if new do your checks.
Thanks.
Reed.

[Richard Clark BS parts]

One of my last Baja race bikes was a 1986 400 WR Husqvarna water cooled monster, a big bike with even bigger power, in those day it was THE fastest desert bike, yes faster  than the Kawasaki KX500 and Honda CR500's. it was the machine, but it had to be set up right.

I remember once.  My ride was factory set up, ran and started well. just did not seem right.  After they investigated it, it was determined that the needle was just one step too low, therefore they lowered the clip one grove, which raised the needle a bit.  The bike just came alive, in mid range it was like ridding a different bike.  I am sure that is all that was done.  The smallest details mean everything.

On  a side note, the next year Husqvarna replaced the 400WR with the 430WR, it was never the same, a step backwards, it just shows little changes mean a lot.



Questions? or need Bridgestone parts? call:

Richard Clark
812-944-1643  8am-6pm EST Weekdays