1990 F2 Wont Rev out past 6k

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Sitnlow4life
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1990 F2 Wont Rev out past 6k

#1 Post by Sitnlow4life » Sun Apr 09, 2017 9:21 pm

Hello

I am rather new to the forum , posted a few times since..

I picked up a 1990 F2 from Canada.

It showed up this past week, replaced the battery on Saturday and took it for a short shakedown run to see if the bike had any major issues...

Everything worked 100%

Move on to today Sunday

I take it out for a spin and about a mile from my home it starts bogging around 6k, no power at all.

I pulled over and it seems to rev fine with the clutch in and idles fine.

Once you apply a load to it , it wont go past 6k.

First thing I thought was plugs, so I added a new set of plugs.

Took it for a ride and the same issue continued.

Gas is fresh 89 Octane Recreational Gas 100% Gasloline.

Any ideas ?

Im thinking of cleaning the carbs to start with, is there a write up anywhere on how to remove them.
I am pretty familiar with 2 strokes from my motocross days, but nothing that was a twin.

Thanks in advance
Todd
1990 RZ350 with Toomey Pipes and Vforce Reeds

AlexG
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Re: 1990 F2 Wont Rev out past 6k

#2 Post by AlexG » Sun Apr 09, 2017 9:30 pm

It could be rich on the main jet. Take a look at the plugs right after Biggs down. Does it work better when the weather is cold. Today in the afternoon was quite warm in Detroit.

steeley
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Re: 1990 F2 Wont Rev out past 6k

#3 Post by steeley » Tue Apr 11, 2017 4:31 pm

Hi ,make sure the power valves are set correctly. as in opening as the revs go up .

evan_calgary
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Re: 1990 F2 Wont Rev out past 6k

#4 Post by evan_calgary » Wed Apr 12, 2017 1:47 pm

Todd,

The twins will be pretty much the same deal as your 2-stroke moto bike. The carbs are just a much more painful experience to pull.

Checking the PVs is a good test. You should be able to see the cables moving on the left hand side of the motor.

From your description it sounds like the bike was working properly for the first mile then the issue arose? I think this is important to confirm.

(F5)
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Re: 1990 F2 Wont Rev out past 6k

#5 Post by (F5) » Wed Apr 12, 2017 4:06 pm

Sounds like fuel starvation. Has the tank been sealed? Blocked vent?
Inline aftermarket Fuel filters rarely sit nicely and kink the fuel lines.

But always clean carbs on an old bike you just bought. Check vacuum hose from carb to petrol tap and that it works.
496 Cheetah. TSS PVs, PWK35s, Ignitech, RGV(ish) chassis

Sitnlow4life
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Re: 1990 F2 Wont Rev out past 6k

#6 Post by Sitnlow4life » Thu Apr 13, 2017 10:35 pm

evan_calgary wrote:Todd,

The twins will be pretty much the same deal as your 2-stroke moto bike. The carbs are just a much more painful experience to pull.

Checking the PVs is a good test. You should be able to see the cables moving on the left hand side of the motor.

From your description it sounds like the bike was working properly for the first mile then the issue arose? I think this is important to confirm.
The bike ran fine for the hour or so I rode it on Saturday afternoon. On Sunday it only ran well for about a mile then this issue arose.
1990 RZ350 with Toomey Pipes and Vforce Reeds

Sitnlow4life
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Re: 1990 F2 Wont Rev out past 6k

#7 Post by Sitnlow4life » Thu Apr 13, 2017 10:37 pm

Pulled Tank

Pulled Carbs

Tested the diaphram on the petcock valve , we are flowing fine in all positions.

The bike had an inline filter on it and I did not see anything inside the filter , I will replace with a new one

Seems to be a very slight bit of rust in tank , I drained it removed the Petcock and heard little bits of something rolling around in the tank.

I made a plate for the petcock and used a gallon of EvapoRust in the tank and every single angle i could think of , this should cure any rust issues that were present.

Sonic Cleaned the carbs

I could not find any smoking gun in the carbs but they were in need of a cleaning , also replaced the needle and seat as well as float bowl gaskets while i was in there .

Also removed the reeds to inspect for any abnormal wear , nothing present .

I also took the time to do a compression test that showed about 135 on each cylinder.

I will put the bike back together tomorrow and try it again.

Fingers crossed...
1990 RZ350 with Toomey Pipes and Vforce Reeds

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Morty
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Re: 1990 F2 Wont Rev out past 6k

#8 Post by Morty » Fri Apr 14, 2017 12:37 pm

Clean the system and get rid of the inline filter more trouble than they are worth
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Forzfed
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Re: 1990 F2 Wont Rev out past 6k

#9 Post by Forzfed » Fri Apr 14, 2017 5:42 pm

(F5) wrote:Sounds like fuel starvation. Has the tank been sealed? Blocked vent?
Inline aftermarket Fuel filters rarely sit nicely and kink the fuel lines.

But always clean carbs on an old bike you just bought. Check vacuum hose from carb to petrol tap and that it works.
That would be my first thought! Especially with rust particles found in the tank.
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Sitnlow4life
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Re: 1990 F2 Wont Rev out past 6k

#10 Post by Sitnlow4life » Fri Apr 14, 2017 11:47 pm

Got it all back together , new fuel line and vent lines.

I forgot which vent line from the carb provides vacuum for the diaphragm on the petcock .

Thanks again
1990 RZ350 with Toomey Pipes and Vforce Reeds

Sitnlow4life
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Re: 1990 F2 Wont Rev out past 6k

#11 Post by Sitnlow4life » Sat Apr 15, 2017 7:09 pm

Morty wrote:Clean the system and get rid of the inline filter more trouble than they are worth
Why are they trouble ?
1990 RZ350 with Toomey Pipes and Vforce Reeds

Sitnlow4life
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Re: 1990 F2 Wont Rev out past 6k

#12 Post by Sitnlow4life » Sat Apr 15, 2017 10:37 pm

Took the bike out for a ride today ...

Same issue as originally stated .....

So now that we know that its not a fuel issue.

Where to next ? Exhaust ? Plugged up silencers ? Dirty Power Valves ?

Electrical ?

Thanks in advance
1990 RZ350 with Toomey Pipes and Vforce Reeds

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Morty
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Re: 1990 F2 Wont Rev out past 6k

#13 Post by Morty » Sun Apr 16, 2017 1:04 am

[youtube][/youtube]
Sitnlow4life wrote:
Morty wrote:Clean the system and get rid of the inline filter more trouble than they are worth
Why are they trouble ?
Because they restrict flow, there is already a screen on the petcock
75 RD350
83 RZ350
87 RZ350
03 KX250
78 DT175

Sitnlow4life
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Location: Detroit

Re: 1990 F2 Wont Rev out past 6k

#14 Post by Sitnlow4life » Sun Apr 16, 2017 2:35 am

Morty wrote:[youtube][/youtube]
Sitnlow4life wrote:
Morty wrote:Clean the system and get rid of the inline filter more trouble than they are worth
Why are they trouble ?
Because they restrict flow, there is already a screen on the petcock
Interesting .....

Think that might be my issue ?
1990 RZ350 with Toomey Pipes and Vforce Reeds

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JanBros
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Re: 1990 F2 Wont Rev out past 6k

#15 Post by JanBros » Sun Apr 16, 2017 6:33 am

Sitnlow4life wrote: Where to next ? Exhaust ?
might very well be if they are choked up.
if it runs, you can race it !

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