Dr Big

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Hi, I bought an 1988 dr750s and I'm having a problem with it. It goes great 1st, 2nd and 3rd under load but when I hit 4th and give it some gas it jerks as if it's loosing spark.......any ideas would be very apreciated. Thanks
Could be there are teeth missing off the dog, or the circlip next to 4th driven gear is broken.
Drop the oil out and remove the plate next to the sump plug (about the size of a cigarette packet and held on with 4 6mm bolts.
You can then see if there is any debris which will give you a clue.
While you are there check oil screen for damage or bits of instant gasket which need clearing.
With a torch you should be able to inspect some of the cogs as well.
If it is a broken gear they will need replacing as pair at about $80 each, plus a complete gasket set and all sorts of special tools
Good luck


Its not the gearbox it's something electrical when under load
Then your first post makes no sense at all
Put it in 5th & labour the engine from low revs all the way up to around five thousand....if you have an ignition issue then it will show up at some point in the range. If not then it is likely to be a gear issue. The fact that the issue is apparent in 4th only is strange & most ignition issues worsen the higher the gear you use due to extra load on the engine.

maybe it needs a new flux capacitor Thumbup


It is worse in 5th, sorry if I didn't explain myself properly before. The higher the gear and the more I demand from it the worse it gets. Are coils problematic on those models? CDI? Stator?
Hi there,

maybe a defect side stand switch?



Sounds very much like a coil on it's way out, is the problem worse when engine is hot??
maybe worth taking off the tank & check connections & earth to both coils.
Let us know how you get on,
Coils and CDI on these old girls are pretty robust and rarely give trouble
Are you sure it`s not fuel starvation due to a blocked filter or similar?
Personally I would start at the beginning and check all my electrics, fuel and carb settings. It might sound laborious but it`s better than making assumptions and following dead ends. Also you get to tick off a very long check list.
In my limited experience in going with Resi, sounds like sidestand switch. As revs and vibes increase the bad connection gets worse. Bypass the switch and go for a ride to see if its fixed.
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