Moped help needed ASAP

I own a moped and usually it cruises at 45 mph. But recently it' been temperaental. Whilst I'm full throttle the bike will sometimes stay at 30 mph and other times goes to 45 mph. And whilst I'm full throttle it loses power and gains power alternating most of the time. Can anyone help me get my moped back to it's self please.

 

give the plug a clean and see if there is any difference. or get a new plug depending how old it is. could be more but keep it simple to start with, check if the variator is tight or/and give it a clean.

 

i guess we need more information to decide if its engine or transmission? does the engine sound likes its bogging, or bad in any way? if so maybe something up with the carb, possibly dirt or whatever. if not then most likely transmission, with it being a little inconsistent id go with the fact that its transmission. Check everything is all nice and tight and intact. also check your belt and rollers for wear

 

I've jus had all the carb all taken apart cleaned and rebuilt but it still does the same thing and with the transmission side I don't really know what I'm looking for. I did take it apart today and it looked all clean but I'm not 100% sure why I'm looking at.

 

ok it's most likely transmission then. you need to take the belt off first as a start I would say. to do this you need to remove the variator. best bet is to watch a video. here's a link to one.


once you have got it off you need to inspect it, checking for wear and fraying. also measure the width. to find that out I'm not 100% sure. search online maybe eBay for a replacement for your model bike see what pops up. if yours is alot thinner that could be it. if not then we move onto the rollers. but let's check the belt first

 

what kind of moped is it ? see if you can get a workshop manual online, it will give you all the sizes, and wear limits.

 

It's a Yamaha jog rr and I just don' understand it it's fine up to 20 mph then does it

 

have you cleaned the carb, jets. blast through the jets in the carb with some wd40 especially the main jet and the channel the main jet sits in, as this will affect the higher rev range. could possibly be some fault with the CDI or ignition circuit timing if its restricting the rpm range but I do not know enough about cdi boxes to help. if you are accelerating as normal the variator can most likely be ruled out. does the engine reach the higher rpm when its on the centre stand ?

 

The bike reach high rpm on the stand then it dies down to a low rpm and I had all the carb and jets cleaned already but it made no diffeence

 

As previously mentioned it is time to learn about the transmission. If the variator rollers are worn or sticking or the variator itself is sticking then a clean and roller replacement will help. If the belt is worn then replace it, as well as measuring the width to see if its shrunk, look for black dust around the transmission casing suggesting wear. Next check the clutch plates are not sticking. Clean and regrease the shaft & pins and check for damage to the shoes and small springs.

 

Thankyou I'll do this tomorrow morning. I just don' understand as it runs fine on the stand but awful off it

 

Did you sort this problem out? The reason it runs on the stand and not the ground is because it’s not under any load so it’s takes no effort for the system to turn the wheel.

 

I guess this depends if he is talking about it idling or revving it up. if revving it up then yes, less force needed on the stand. but if we're talking idling that's a different problem. could be fuel related. I've had a similar problem before

 

No it' still not sorted. It's in the garage as we speak until next week. Hopefully it will be sorted when it comes out.

 

Hi, was just wondering if yuo managed to get the bike sorted?

 

I took it to the garage and it's all sorted now. It was in the garage for 3 weeks but yes it's done
Thankyou

 

sounds good. what was the problem?