ian
Member Of The Year 2019
Isle of Man
Posts: 5,267
mini-profile background: {"image":"","color":"29908d"}
|
Post by ian on Aug 29, 2014 19:40:14 GMT
First thing is to check the sprocket sizes - people seem to play about with the gearing quite a bit on the 250s. When I got mine, it seemed to run out of steam about 5000rpm & struggled up hills. When I replaced the chain & sprockets, I found it had a bigger rear sprocket, raising the gearing quite a bit. I can see why someone would do this = it's more relaxed if their commute was largely flat & straight, but the standard gearing is much more suited to the hills & bends I ride on. With the standard gearing, mine's doing just under 50 at 5000 & just under 70 at 8000, which it pulls easily. I've not been over that yet as there's always been a bend approaching by then
|
|
|
Post by grahamb on Aug 29, 2014 20:12:34 GMT
It does seem wrong, I'm getting 60mph at 4000 revs I have not had a 250 but my 400 will not do 60mph at 4000 rpm . Are you looking at Kph or your gearing is not standard.
|
|
|
Post by Fordy on Aug 29, 2014 20:40:23 GMT
It's all standard as far as I'm aware, of course the rev counter may not be accurate but that's what it's saying.
|
|
|
Post by greybeard on Aug 29, 2014 20:41:51 GMT
Likewise - 60mph at 4000rpm sounds totally wrong. I would say your tacho is under-reading by quite a margin.
My 250 today was pulling 50mph at around 5250rpm.
If the wind dies down a bit tomorrow I will go at do a check run along the local dual-carriageway - top speeds at increments of 1000rpm. Mine has standard sprockets.
|
|
|
Post by Fordy on Aug 29, 2014 20:51:01 GMT
Likewise - 60mph at 4000rpm sounds totally wrong. I would say your tacho is under-reading by quite a margin. My 250 today was pulling 50mph at around 5250rpm. If the wind dies down a bit tomorrow I will go at do a check run along the local dual-carriageway - top speeds at increments of 1000rpm. Mine has standard sprockets. how do I check if the tachometer is under reading? Or is it a case of changing the cable. When I rev the engine in neutral the revs go up to the red so I'm not sure
|
|
|
Post by greybeard on Aug 29, 2014 20:54:19 GMT
Honestly? I havent a clue!!!
Thinking about it, other than the tacho under-reading, could your speedo be over-reading?
|
|
|
Post by Fordy on Aug 29, 2014 21:07:29 GMT
No I think the speedo is correct as I was doing 60mph behind my daughters car on the weekend, and she confirmed this.
Anyway it's slow enough without thinking I'm going even slower than I thought!
|
|
terryc
Forum Accommodation Specialist
I'll put you up ,plenty of room in my box
Posts: 5,308
mini-profile background: {"image":"","color":"29908d"}
|
Post by terryc on Aug 29, 2014 21:40:41 GMT
I'd start with a new cable if the square ends are rounded off the cable could be spinning slower than it should if its not that then its the clock itself thats at fault it may be repairable but I dont know for definate if they can be repaired or if you will need a new clock as well
|
|
|
Post by Fordy on Aug 29, 2014 21:57:39 GMT
First thing is to check the sprocket sizes - people seem to play about with the gearing quite a bit on the 250s. When I got mine, it seemed to run out of steam about 5000rpm & struggled up hills. When I replaced the chain & sprockets, I found it had a bigger rear sprocket, raising the gearing quite a bit. I can see why someone would do this = it's more relaxed if their commute was largely flat & straight, but the standard gearing is much more suited to the hills & bends I ride on. With the standard gearing, mine's doing just under 50 at 5000 & just under 70 at 8000, which it pulls easily. I've not been over that yet as there's always been a bend approaching by then I'm wondering if a previous owner has changed the sprocket as it really does struggle up hills, how would I check this?
|
|
|
Post by grahamb on Aug 29, 2014 22:09:17 GMT
Simply but either seeing if the sprocket is stamped with the number of teeth or counting them .
I'll have a look in the manual to see what they should be unless someone beats me to it
AS FB has posted 15t front 41t rear
|
|
|
Post by greybeard on Aug 29, 2014 22:10:01 GMT
By counting the teeth in the primary and secondary sockets. I would need to check the specs in the workshop manual for what they should be....give me a few minutes.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Aug 29, 2014 22:15:33 GMT
15/41
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Aug 29, 2014 22:16:13 GMT
16/36 on the 400......
|
|
|
Post by greybeard on Aug 29, 2014 22:27:52 GMT
Ah - I see the experts have arrived!!! Excellent, because I am buggered if I can find the info..........
Thanks Nick!!
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Aug 29, 2014 22:31:35 GMT
It's engraved on my pencil case.
|
|