750 Sport, fuel pump or ignition problems ?

discussion about the 750 Sport and '89/'90 900SS, which share many mechanicals with the Paso series
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Posts: 1
Joined: Wed Jul 29, 2015 8:04 am
model: 750 Sport
year: 1988
Location: Sweden

750 Sport, fuel pump or ignition problems ?

Post by Winder »

Hello you nice motor cycle doctors,

I´m having a problem with my 1988 Sport. When I start the bike it runs very well for about 15 minutes then it starts to blurr and shake and losses power. I have to drive slow for about 5 minutes then it wakes up again. Full throttle and it sings again...... for 5 minutes.. back to shaking mode, lack of power. My first thought was fuel pump problem but now i am into ignition problems. Over heating of coils ? Please, could you give me some ideas how to solve the problem ?

Kind regards
Bo from Sweden
Mc tool
paso grand pooh-bah
Posts: 1856
Joined: Wed Dec 05, 2007 12:35 am
model: 906 Paso
year: 1990
Location: Newzealand

Re: 750 Sport, fuel pump or ignition problems ?

Post by Mc tool »

Sounds like it's dropping one cylinder. What sort of carbs does it have ? 2 barrel Weber or 2 single carbs ?. Could be a fuel flow issue to one csrb if single carbs are fitted ( check float valves ). Are you able to get your hand on the coils to check the temp ( reaching under fairing )? And ,probly pay to give the wiring a good check over too. :)
I wish I was young again............Id be heaps smarter than last time
Posts: 7
Joined: Mon Dec 07, 2015 6:16 pm
model: intending to buy a Paso/Sport
year: 1999
Location: Belgium

Re: 750 Sport, fuel pump or ignition problems ?

Post by lodola235 »

I also have an 750 sport(bj90)
I had already mounted an mikuni from an 900 SS (hope to put 2 dellorto's later) wich solved bad starting, and an smoother run
now, my voltage regulator blew up, and I'v mounted an ignitech CDI(plug and play) and an camro voltage regulator (2 wire connection instead of 3 , just isolate 1 wire instead of connecting two together like the manual says) , everthing seems an improvementant I've mounted an yamaha TRX vacuum fuel pump instead of the electric one wich had too much fuel pressure (was an bit more work to bore out the fuel tap where the old fuel line was brazed on), have done already little distance but not an long ride ; but it seems to work ok
paso grand pooh-bah
Posts: 1521
Joined: Thu Jun 21, 2007 12:00 am
model: 907 I.E.
year: 1991
Location: Gothenburg, SWEDEN

Re: 750 Sport, fuel pump or ignition problems ?

Post by Tamburinifan »

Vacuum fuel pump can be semiworking, due to bad diaphragms. There are replacement avaliable.

907 I.E. -91
M900 -97
MTS 1100s -07
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