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DT50mx running problems


volvoboy73
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Hi all, 

I've been restoring a DT50MX for the last year or so and after giving it a run around the block it's clear that not all is right with it! 

I suspect it's carb related, it runs ok at small throttle openings but anything more than that and it just bogs downs and will die unless I back off the throttle, occasionally it will rev out so I'm wondering if it is suffering from fuel starvation (when it dies it's similar to running out of petrol).

So, where to start? Should I alter the height of the float in the carb?  

Any advice / suggestions welcomed!

Cheers.

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  • Moderator

Nope, leave the carb.

How much restoring have you done, new everything or a clean and tidy.

New bore and piston? coil, plugs, wiring etc etc.

Have you had the carb apart, cleaned inside. 

We cannot see what you can, can you fill out the picture a little, bogging down could be any number of things, least of all float height.

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Hi, thanks for getting back to me. 

First of all I apologise if I've posted this in the wrong area of the forum, maybe workshop would have been more appropriate?

As for the bike, it's been more of a good tidy up and sort out than a nut and bolt resto.

I've replaced the HT lead, battery, plug cap and plug on the electrical side of things plus got all the lights and indicators working again.

As for the carb, I've stripped it totally down today, all the jets looked clear but I blasted everything through with compressed air, when it went back together it was spotless inside and out. The thing I saw that slightly concerned me was that the male part of the float valve seemed worn on the taper (a small step in it) although it seemed to seal ok when I blew through the inlet pipe. I did a plug chop after a run and the plug seemed about the right colour and was not wet with fuel. I've checked the breather on the petrol cap and the reason I think it might be fuel starvation is that if I potter along at low revs it sometimes pulls well and revs out but try it a second time and it bogs down and I wondered if the float bowl was struggling to fill up fast enough to maintain high rev running.

I've set the mixture screw to 1 and 1/2 turns out from fully in.

 

Thanks again.

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  • Moderator

Have you opened the engine up. Checked things like piston gaps and bore wear. 50s live a hard life and wear badly due to neglect when they get to rat status.

Cannot see fuel starvation from worn float needle, bad plug gap, points or condenser (unless its electronic) would be my first call.

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