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Discussion Starter #1
Hi. I bought a 2002 Honda fx650 vigor. The piston was knackered. So I got a new barrel and piston (2nd hand) and removed all the old piston from the engine. It has 75-80psi on compression. And the valves have been set to 10mm? What ever it is in the Haynes manual. It semi fires. Goes to around 800-900 rpm. But won't carry on. Any ideas.

Many thanks
Owen
 

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80 psi is far too low - it should be at least 140. And 10mm (if that's the valve clearance) is ridiculous.......
 

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Discussion Starter #3 (Edited)
My bad. I ment 0.10mm. How else can I give it more psi. The barrel and piston and in good condition. And all new gaskets.

Just checked the manuAl. It says 92psi
 

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Don't forget that the automatic decompressor reduces the effective compression when cranking over. You're not too far off at 80psi.
If the bike has been standing it will be a Sh*t to get it going.
Make sure you're using fresh fuel, drain the float bowl and refill if in doubt.
Remove the airbox to carb snorkel and put your hand over the carb mouth to increase the suction.
Is there a good spark?
 

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Discussion Starter #5
Hi. Thanks for a reply. I have removed the carb and cleaned it out about 3 times. It has a good spark. And new plug. Fresh petrol.. fully charged the battery. Used easy start (alcohol so helps the engine fire) still nothing.

The bike was stood up for about 8-10 months in dry storage. All electrics work. So I'm not thinking it's the cdi/ecu.

Honestly I have worked on it. It just p*sses me off every time I work on it. As it only needs a few hundred rpm to carry on.

I was thinking of advancing the timing. And seeing if that would help but not sure.

And I'm completely out of ideas of why it's not running.

Thanks for the reply.

If you think of anything else please reply. I was very close of pushing it off a cliff. But it's too heavy to push up hills...

Many thanks Owen
 

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I dont think you can change the timing TBH, where are ya in Devon ?
 

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Unlikely to be timing....
If you have good spark unlikely to be side-stand switch etc.
Is the plug getting wet with petrol when you try starting?
 

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Second piston and barrel sounds like a recipe for a shit engine.

Theae motors will run with surprising low comorss though, although not well.

Ia everything else on the bike standard ??



Sent from my G7-L01 using Tapatalk
 

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Discussion Starter #10
Hi. When I got this bike the barrel and piston where shot. I mean. The piston exploded. So stripped the engine and removed all the piston. So bought a slr650 barrel and piston from a working bike.

The head is OK. And so are the valves.. complete new gaskets as well.
 

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Discussion Starter #11
Hi. The plug is dry but black with carbon.also it's a new plug. Have tried pouring petrol into the venturi and no improvment took the plug out and put a little petrol into the bore put plug back in. And still no improvement....
 

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I would like to heard about wet but clean spark plug.
You could have a duff new plug - try a cleaned old one.
Are 100% certain cam timing is correct?
 

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Discussion Starter #13
Hi. The timing is done right. I followed the manual. (Also I have been to college for motorcycle repairs) but this bike is just a pain.
 

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If there's no fuel getting through then surely that needs further investigation - is it gravity fed from the tank or vacuum operated fuel tap?

Though odd that that even with easy start there's not a hint of it catching.
 

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Discussion Starter #15
i think its gravity fed, (I think)
the bike fires and smoke out the exhausts, but it wont carry on, it gets to about 900RPM and it needs a few 100 RPM to carry on. when its running at 900ish RPM i then put a little bit of easy start, it just dies. I know this is over fueling it, but will a small amount of easy start shouldn't kill an engine and make it stop (fuel mixture is set to standard)

Many Thanks Wychwoods
 

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i think its gravity fed, (I think)
the bike fires and smoke out the exhausts, but it wont carry on, it gets to about 900RPM and it needs a few 100 RPM to carry on. when its running at 900ish RPM i then put a little bit of easy start, it just dies. I know this is over fueling it, but will a small amount of easy start shouldn't kill an engine and make it stop (fuel mixture is set to standard)

Many Thanks Wychwoods
A small amount of easy start will kill an engine off idle. Its for starting, nothing else. It can work with your throttle wide open but ive rebuilt and fixed countless of these motors and easy start has NEVER worked.

If your bike will run on idle but die on anything past idle then it can only be a few things.

Either your carb isnt fueling enough (perhaps blocked float valve or blocked main jet). Sounds like its only running on the pilot circuit to me. Loosen the carb drain screw. Do you get a constant stream of fuel with the fuel tap turned on ?

These motors, like all motors have a timing advance. On these specific engines, its called a timing 'boss' and its what the pulse generator picks up on

When the timing boss or CDI has been changed and is incompatible, your ignition wont advance past idle (common problem when people put SLR, FMX motors in dommies and vice versa).

Your coil is bad (Buy a new genric two-pin on ebay for £10)

This is all assuming your valve timing snd second hand engine parts are okay. However, If the bike will idle then it should also rev-up

Good luck
 

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Discussion Starter #17
Hi. I can't get it to idle. It's just under idle.

I will try and clean the carb out again and go in with a toothbrush and clean it 100% not just a general clean...

The bike was running before the piston exploded. And I asume all electrical parts are the same and not changed.

The coil replacement might be a good idea.

I will try to make a video and upload so you guys can see what's going on.....

Many thanks Owen
 

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Apart from the good idea about new Coil, it does sound carb related.
Are you certain neither of the carb diaphragms are split or damaged and vacuum circuit not blocked or perished.
I would set Idle Mixture to 2.5 out not standard
 

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Remove and earth the plug against an unpainted part of the motor and turn it over. You need a constant, fast bright spark.

Sent from my G7-L01 using Tapatalk
 
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