Topic: 1973 350F bogs under load

[pacific_muscle75]

I'm pretty set on buying a 73 350f from my cousin soon. he says it will rev fine up to like 8k when in neutral and have awesome throttle response, but when in any gear it seems to loose power right around 4-5k. He describes it as boging, which makes me think its running too lean and starving itself. He said the carbs have been off it and "cleaned", but not sure who did, or how well they were. and the only aftermarket part was straight pipes.

The guy he has doing it, said that it might be a lack of back pressure, but I have been told that a cb350 will run fine without pipes. he said it sat since 1984 before he got it running, so he had the carbs cleaned and the tank cleaned, but maybe they missed the petcock?

I don't know about these models, any ideas would be a great help.

If it matters, he said around $500 so im very interested

[mlinder]

Probably a vacuum leak, or a cylinder not firing. Also, these little guys need to be in a good state of tune to run properly.
Normal #$%*. Valves, plugs, timing, clean carbs, carb synch, good AF ratio.

[kghost]

Its hard to diagnose based on someone elses remberance of wgat was done when...

Start with a basic tune up....Then set the valves and the Cam chain tension.

Then make sure the carbs are synced.

I'll tell you from experience that the 350F is touchy when it comes to Jet size.

Straight pipes with no Restriction usually = jet change

[mattcb350f]

I'll tell you from experience that the 350F is touchy when it comes to Jet size.

I agree. mine is almost too lean on a cool morning and noticably rich in the heat of the afternoon 

I guess it's spot on 

 Matt.

[Johnny5]

Good fuel flow?

[bender01]

What jet size would be recomended to start with on an open exhaust? 80-85?

[pacific_muscle75]

Does anyone think that there is any reason that the exhaust will actually cause physical harm to the engine? I mean like burned this, cracked that. I know it will affect the performance either for good/bad, but Im more concerned with prolong the life of the bike, rather than getting the best from it.... although the best from it would be good too.

can anyone recomend a good place to get jets and what size I'm looking for.
and where might I get a fuel petcock from if/when I need one.

[mlinder]

Does anyone think that there is any reason that the exhaust will actually cause physical harm to the engine? I mean like burned this, cracked that. I know it will affect the performance either for good/bad, but Im more concerned with prolong the life of the bike, rather than getting the best from it.... although the best from it would be good too.

can anyone recomend a good place to get jets and what size I'm looking for.
and where might I get a fuel petcock from if/when I need one.

You wont damage anything with that exhaust.

Again, BEFORE you start buying stuff, tune the bike up completely, and then lets look at your plugs, ok?

[pacific_muscle75]

Does anyone think that there is any reason that the exhaust will actually cause physical harm to the engine? I mean like burned this, cracked that. I know it will affect the performance either for good/bad, but Im more concerned with prolong the life of the bike, rather than getting the best from it.... although the best from it would be good too.

can anyone recomend a good place to get jets and what size I'm looking for.
and where might I get a fuel petcock from if/when I need one.

You wont damage anything with that exhaust.

Again, BEFORE you start buying stuff, tune the bike up completely, and then lets look at your plugs, ok?

Thats great advice. does anyone think I shouldn't buy the bike for only $500? what are dead-ringer sings that it's a money pit ...

[kghost]

Well....While the exhaust won't hurt anything....Running around with it LEAN will.

Its only 350 CC so to get any usability out of it....it pretty much has to be tuned right.

Its not like a single or a twin....all the cylinders have to be working together or performance is dismal at best.

Additionally most of the usable power is above 5000 RPM....doesn't do a whole lot until then.

[pacific_muscle75]

No kidding!! I've read the horo stories of lean conditions and have seen plenty of burned through pistons in books. Scary Stuff!! Im hopefully going to go look at it here pretty soon, and the first thing I want to do is pull the plugs to see what they look like.

I apprecieate all the responses so far, and look forward to the coming ones.

Happy Memorial Day to all!!!