Topic: Honda cb350f top speed

[markreimer]

I'm no expert on plug colour so I'll leave that to someone else. But 85 mph at 107kg sounds like your motor is running pretty well to me.

[grcamna2]

I was tucked in today and got 85 mph I weigh about 107 kg
I did a plug chop as well the first one is at full throttle and the second is at idle
Here is the pictures ,what are your opinions

Those plugs look a little oily imo,possibly your piston rings haven't broken-in yet.This is difficult to see/identify by only pics.

[Scooterhead]

Is it the right sort of tan?am I heading in the right direction with the mixture screw and main jet

[flybox1]

1/5th turn richer (in) on those air screws

[Scooterhead]

Thanks flybox1 I have done that ,it feels a little flat at wot and I can only get about 85 ish mph my speedo is dead accurate at 60 mph
The mains are 80 but as you know exhausts are non baffled 4-4
The plug chop at wot shows slightly tan core ,what colour tan should it be,should I up the mains slightly?

[Scooterhead]

Tried 88 mains jets instead of 80 and the result was not better but worse
At wot it stumbled a lot until I backed off,if I added some choke it got really bad
I guess this means it's now to rich but the plug chop at wot only really showed a black like rich spark plug ring slightly confused
I think the claimed 98 mph top speed is out of the question here it must of been a plastic dummy riding it.

[grcamna2]

Do you run the stock airbox ? I've always liked using the stock airbox along with a high flow Uni foam aftermarket filter element;the stock air box helps the engine w/ the proper power curve.I would think your 80 mains are good.. imo.

[Scooterhead]

Yes stock air box and filter,it didn't like the 88 mains at 3/4 to full throttle I think I'll go back to 80 mains

[carnivorous chicken]

I think the claimed 98 mph top speed is out of the question here it must of been a plastic dummy riding it.

You're not going to get to 98. Depending on your weight, engine compression, etc., I'd say getting to 85 is doing just fine.

[Stev-o]

The horsepower gain/weight reduction diet is something everyone oughta try at least once.

I religiously drop 2lbs before every ride 

Into the toilet?!

[Scooterhead]

Does anyone know what the compression should be  for 350f

[TwoTired]

About 170 psi if you use the Honda guage or a small engine tester.  Much lower if you use an automotive or diesel compression tester intended for larger displacement engines.

You might consider a leak down tester instead.  Particularly if you can't obtain a small engine tester.

[innovativems]

With your bike are all four cylinders within 10% of each other?


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[Scooterhead]

Yes I have a small
compression tester that I got off eBay
They all measured about 150 psi well within 10% of each other
Re built engine with new piston rings the book says 150-170 psi and it done 600 miles since re build.i was hoping for the 170 psi especially after r build

[innovativems]

I wouldn't worry about that compression.  Do a leak down and check your valves sealing


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[Scooterhead]

I sorry mate but how do you do a leak down test

[MoMo]

I sorry mate but how do you do a leak down test

First you need a leak down test kit.  HF does sell one...Larry

[Stev-o]

I sorry mate but how do you do a leak down test

Here....

http://forums.sohc4.net/index.php?topic=152902.0