Bike starts runs and then dies and doesnt start till later

Questions regarding the DR750

Bike starts runs and then dies and doesnt start till later

Postby Gavinnash25 » Wed May 23, 2018 6:28 pm

I have a dr750 an 1988 model.
Bought it on a farm in pieces, so the 750 carbs were non repairible, so I got the 800 carbs on ebay. Bear in mind that I am not a machanic and learning as I go along. The bike starts with a touch of a button and idles well. Then at some stages it will go up and down. When I take it on the road she will drive fine for about 3_6 km. And then will cut out and then doesnt want to start again. Only after about 20min or so it will start again. The fuel pump has a new kit in. I am realy at a loss hear. Can any body help please, I have bean working on it for over a year
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Re: Bike starts runs and then dies and doesnt start till lat

Postby H_Lime » Thu May 24, 2018 3:31 pm

Someone smarter than me will be along shortly but assuming the carbs are good sounds like a coil breaking down as it gets hot to me.
How are the valve clearances too?

Might also be worthwhile to know what voltage shes making when this happens, if she drops below 12 v and the batterys marginal it will stop ya.
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Re: Bike starts runs and then dies and doesnt start till lat

Postby BigBob » Fri May 25, 2018 11:18 am

Even if your carbs were set up perfectly they would still be running rich as they are for a 52cc bigger engine, but they would not cause the problems you have.
It sounds like your carbs are being overfuelled, so either your fuel pump isn`t working and 29 litres of fuel pressure is causing the carbs to flood, or more likely, the float level is too high causing the same effect. The float needle housing has an O ring that tends to crack and perish if left standing for any length of time which will allow neat fuel into the engine, though I don` think it`s likely to be the culprit on this occasion.
Setting the float levels on these carbs is a bit hit and miss at the best of times and the manual is no bloody help at all. Ideally you would find the correct 750 carbs at some point.
If you were local to me in Essex I could help you set the carbs up properly.
Some bikes have coils that are prone to failure but in 30 years of Big ownership I`ve never heard of one failing. Besides, I remember a plug packing up once and I rode home about 50 miles with just the one working and it rode perfectly fine, though it was slightly down on power.
I think you need to set the float heights correctly by moving the tang closer to the float needle. Best done with the carbs on their side. Check exactly how much you have adjusted the tang by, so that you can always set it back to where it was, and remember, just 2mm will have a significant effect.
I`m writing this assuming you haven`t been an utter fukkwit and kinked a fuel line (we`ve all done it) and hopefully you will have used genuine Suzuki fuel lines and not cheap Chinese lines that will eventually split and spray fuel all over a red hot exhaust. An incinerated scrotum is not funny. ;)
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Re: Bike starts runs and then dies and doesnt start till lat

Postby Gavinnash25 » Fri May 25, 2018 3:19 pm

Your not popping in to cape town south africa soon :D
The lines are not kinked and the vacuum pump has n new kit in and working great. I took it to a guy I know and he said that because the bike was standing for a couple of years the valves might not be seating correctly and this might cause it to cut out when the engin gets hot. Do you think this might be it. I think I will have the valves checked out anyway.
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Re: Bike starts runs and then dies and doesnt start till lat

Postby BigBob » Sat May 26, 2018 8:39 am

Last time I was in Cape Town was 1982 and as I`ve no plans at the moment to go back, it`s unlikely I can check your bike over for you.
It`s not unknown for valve faces and seats to fur up if left standing but if it starts and runs for a few miles then that`s not your problem. It would run, albeit a bit poorly, if the valve faces/seats were not seating well and improve as they bed in, which they tend to do quite quickly when they are bashing together several thousand times a minute.
I really think you need to concentrate on the carbs first. Were the carbs you got 42 or 43?
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Re: Bike starts runs and then dies and doesnt start till lat

Postby Gavinnash25 » Sat May 26, 2018 4:49 pm

Im not sure what dr800 carbs it is, as I could not find carbs in south africa and found the 800 carb and the fuel pump on ebay and inported it from the uk. At that time there was not any 750 availible, and I was desparate to get the bike going. The set I bought has only one air/fuel screw for. I do still have the parts of the 750 carbs, but the casings are broken. Should probebly look at swopping the jets. Trying to keep it origenal, as the bike was in pieces. I have found a guy that works on carbs and will take it to him in the week. Will one be able to set the 800 carbs correct by changing the jets? I am learning as I go on as I have very little machanical experiance. But google alot and try to do thing on my own as I dont always have the cash for bike macs. Its been over a year building bit by bit, but im sure I will get there at the end.
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