2006 Honda SH125i bogging down.

[lucazade]

Hi Guys and welcome,

This is my 1st post so also my introduction.

My name is Lukas and I am all motorbikes for well forever (do not even own a car as seem that as stupid in London with my usage).

I mainly ride Italian bikes as they are the most reliable in my view (yes yes I will get to that).

I had a CBR125 as my first bike, broke down 3 times in 9 months
Monster 750 - No issues sold to get 749
749 - No issues, sold as had to
M900 - One major issue as seller lied to me but now sorted (currently in parts for another project build)
900SSie bought cheap, run to the ground (over 40k with minimum service) then sold for parts
996 Bip No issues but now sold due to change of situation

Recently I bought myself a scooter to have a reliable cheap ride and it all went wrong.

It is a 2006 Honda SH125i, 4 stroke. It had 15k on clock when I got it (now 16k) and was in a small bang as evident by broken plastics. Other then looks rode perfectly, starts at a button till today, brakes and so on.

About 1 month ago had an issue of it being under-powered and bogging down not from start but rather when I reached certain speed.
Was thinking rear brake failed as that is how it felt like, like dragging rear brake. Maximum speed I could do before it stalled was about 15-20, if you had down hill maybe 30. 30-35% of throttle max open before it started bogging down. Pinning it made it struggle and eventually stall.

Sent it to mechanic, he had a look at brake found not wrong so I said fix it please.

Since then he fitted another fuel pump (all from working bike), no change, new clutch no change, another injectors no change, another CDI unit no change, new belt, rollers, air-filter (aka service) no change so I took it back as it started being silly.

Currently bike has its old parts back plus new clutch, new rollers/belts/air-filter/spark-plug on.
I can start it at button and rev it all the way to top when stand still (pin throttle full open instantly and it revs freely) with no odd sounds or it struggling.

Did my own experimenting and with fuel tank open I can ride easy to about 30 mph. Long road even 40 mph or climb huge Wembley hills at 30mph. It does not seem to be load issue alone. As long as I have throttle not open more then 40-45% all is good. Anything above that it looses power, becomes rattly however if I pin it full now it will just sound bad, neither accelerate or slow down just stick to about 30.
Pinning it from stand still to full throttle gives me about 2s before it starts bogging down.

On top of things done I also checked spark-plug and it is white so suggest to me lean, removing exhaust changes nothing so not blocked exhaust.

Any suggestions what is wrong with it?

Thx in advance. I just want to fix it and sell it on no matter how reliable it becomes. I lost trust in it.

[bikenut]

change this change that change bike!!!!!!!!

has the mech checked stuff like does the cdi ign system work properly like does the ign system "advance" like it should?? due to a bad connection of failed advance stator etc etc etc

check stuff before you change stuff as if its going out of fashion.
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[lucazade]

[bikenut]

yes, get him to check the ignition advance with a timing light to rule that out. or in as the case may be.
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[davebike]

I would start by doing the one service bit not mentioned Check the valve clearances
I seen these bike close up the exhaust valve are run very poorly yet still idle nicely

Dave
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Dave
NC750Xdct + others at work !
davebike1@gmail.com

[bikenut]

:D very good point dave!! :karma:
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