Honda XRV Forum banner
1 - 7 of 7 Posts

·
Registered
Joined
·
36 Posts
Discussion Starter · #1 ·
I got me one of these:





Now I wasnt expecting much but there really isnt much power at all!

Bizarrely there is a bit of torque and it will "torque" its way up a reasonably steep hill off-road in 2nd but there just doesnt seem to be any midrange, and you have to rev the nads off it in a lower gear.

I've gone through the bike and all seems fine, though I found blocking off a large part of the air box top that had had the snorkel removed improved midrange noticeably.

The only other thing is the previous owner opened up the guts of the silencer, and though its by no means a straight-through I'm wondering if the reduced back pressure has had an effect?

I tried a bigger main jet, 95 up to 98, but it ran far to rich and spluttered, and raising the needle also had no real effect.

Has this thing just not got any midrange, or how can I get some :)
 

·
Registered
Joined
·
207 Posts
sadly you have the bike with the ohv engine, it has little power, mind you the ohc engine has not got much for a 125.
if you can ride a bigger bike then i would get one as trying to get it faster is a waste of time and money.
you may be able to get an xl/xr 200 engine to fit but the electrics, carb ect will all need changing so a lot of money, if you want a faster 125 then get a 2 stroke one, not a 4 stroke!
 

·
Registered
Joined
·
36 Posts
Discussion Starter · #3 · (Edited)
Thanks for the reply. This is the OHC engine actually, same as fitted to the CLR125 City Fly.

And, yes, not much power :)

I do have a bigger bike but wanted to use this when the weather and/or conditions are bad and speed is not so much a concern, but even so....

I further reduced the airbox lid opening, and shoved in slightly more restrictive piece of pipe in the exhaust. This has boosted low-end power noticeably (well, from not a lot to just a bit more) with no obvious loss to top end so its usable at least now.

Think I will try and source the original airbox snorkel and get it back to how Mr Honda intended and start from there. I have been through the bike, air-filter, valve clearances etc and its all ok....
 

·
Registered
Joined
·
207 Posts
yes, sorry i miss read it i thought you had the xrl!
that does have the ohv engine.
not really much you can do to make it faster, except shove in a 200 engine, as it will fit.
good luck
 

·
Registered
Joined
·
14 Posts
Sigh!
Re OHV (ie. 'pushrod', they all have overhead valves),
All older XL125 be it XL125R XL125S XL125K had a SOHC engine. They all make 12 or so BHP which wasn't too shabby when this engine was conceived in the early 1970s. The pushrod CG125 also made about 12bhp.
Your SOHC 125 is possibly quite tired, or poorly rebuilt, or just set up wrong. You should be able to happily hit an indicated 65mph in 5th. 6th may be a bit high to pull max revs.
These little engines do wear, so if it was mine I'd have it apart and check the cam for wear, the valve seats, and it will probably benefit from a re-bore. Check also the crank big and small ends for wear, though this wint dramatically affect performance.
An easy way to get more torque and mid-range power is to rebore to take a CB550 +1mm piston. This will give you 138cc and raise the compression ratio a bit. DO NOT rebore to 150cc (actually 146cc) UNLESS you also fit a thicker cylinder liner. The 138cc option is affordable. The 146cc probably not worth it for 8cc more.
To me, your engine sounds to be worn and tired and needing a rebuild, checking the areas I already mentioned. The carb will by now have had many "experts" fiddle with it. Look on eBay, you can get new Mikuni carb from USA for about £35. That's less than a Saturday night out! Block the additional holes in the airbox, and leave the exhaust till you've done everything else.
Al.J
 
1 - 7 of 7 Posts
Top