I have a Yamaha DT50W with poor low end power. Engine runs fine at high rpm but bogs at low rpm and will not pull up hill without reving engine and clutching. Engine responds normal with no hesitation on level ground and does not stutter at all just reving throtle in nuetral. Is it worn rings piston or just cause its a 49cc??? Bought used with 1100 miles.

Bad ignition coils will make the truck act like this. Also low fuel pressure.

incorrect air fuel mixture or a leak check for damage to the intake boot or airbox

i need to know more about how its running at low mid and high rpm to help you troubleshoot and you need to check for leaks especiely the intake boot if the intake boot is leaking that will need to be fixed before running the bike asumeing that is ok or fixed run the bike listen to it at idle standing is it surgeing with a good fast acceleration off the line with you siting on the quad ? or just realy rough ticking over with little guts off the line ?

midrange rideing how does it feel is there a bwarrr noise as u accelorate hard or does the engine roar up fast

is it reaching a good top end with good pulling power or poor pulling power

are the backfires constant or mainly whyle slowing down from high revs

if all are effected but there are no leaks then it may be float / fuel level that needs ajustment fuel level in ur float bowel effects all stages of rpm low mid and high

A rich problem gets worse as the engine heats up.



A lean problem gets better as the engine heats up.



hope this helps if u dont fix it your self first try and do them little rpm backfire tests for me itl tell me a lot

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These will help.
Thanks.

most likly needs new rings-or bad plug if you are lucky

if you drive on hills at high rpm ur engine temp. will surely shoot up due to the load on ur engine while trying to gain the desired speed/ u should not drive uphill with high rpm try to maintain low speed with low rpm

This could be a TPC valve or sensor. That is a throtel position control. Your engine will idle or run at low speed fine or in stop and go traffic but highway driving or climbing a hill when the demand changes to heavy or light consumption it will surge the engine as it can't get a good read on what it is suppose to do. This is a resonable priced part and for about twenty bucks for a CHILTON manuel for your car it will give you step by step instructions on this and almost any project you want to try yourself. They will have these at your autoparts store.