Part throttle probs

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trix
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Posts: 52
Joined: Fri Dec 01, 2006 2:25 pm
Location: Norn Iron

Part throttle probs

Post by trix » Wed Sep 07, 2016 9:47 pm

Hi guys
Just wondering if anyone can help with this;

Symptom; cruising along at part throttle at about 3500 rpm, and engine hesitates/misses. If I open the throttle further it pulls out of it and accelerates ok. Problem only occurs at part throttle and at about 3000 to 3500 rpm or so.

I thought it might be the throttle position sensor but I've measured the resistances etc and they check out fine and the rev needle points at 4000 rpm when doing the diagnostic check so it seems to be fine.

Any ideas?
TRX850
RD500
CBR900RRX
NS400
RS250
KR1S

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dandywarhol
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Joined: Fri Nov 24, 2006 12:56 pm
Location: Edinburgh, Scotland

Re: Part throttle probs

Post by dandywarhol » Thu Sep 08, 2016 10:25 am

Search "emulsion tubes" and maybe get a Litetek viton seal kit.
1996 TRX 850, blue, Ohlins 46HRCLS, Race Tech Gold Valves, 0.90 springs, Venom pipes, R6 brakes............
1974 Yamaha RD250A, Candy Blue
1998 Yamaha SZR660, blue of course
1967 Yamaha TD1C 250, Blue and white

trix
TRX-Enthusiast
Posts: 52
Joined: Fri Dec 01, 2006 2:25 pm
Location: Norn Iron

Re: Part throttle probs

Post by trix » Thu Sep 08, 2016 5:23 pm

I changed the emulsion tubes a few years back and havent done huge mileage. The problem is kind of intermittent too. Perhaps a bit worse when its warm??
TRX850
RD500
CBR900RRX
NS400
RS250
KR1S

ekoja
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Location: Gold Coast Australia. GOOOSD.

Re: Part throttle probs

Post by ekoja » Fri Sep 09, 2016 2:40 am

You might want to check the small white plastic caps on the side of the carbs ,especially the right side card ,(as you would sit on the bike). They are prone to cracking with age.There Is a thread on here about this very problem but I couldn't find it.

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