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CBF 125 Tappets At 40,000
Blog Date - 07 August 2015
Well the owd CBF 125 now has 40,000 miles on the clock! That's not bad going for a 125 I reckon. Since my first issues with the tappets going tight due to me being a lazy git and not blinkin checking them I now keep an eye on them. I started out checking them every 4k or so but since they've barely moved I now check them every 10k. The manual suggests they should be done every 2.5k but I mean come on...really?
So being that 40 is a multiple of 10 it was tappet check time. Last time at 30k they didn't need adjustment and I am proud and pleased to report that this time they are both within tolerances. The inlet valve is a happy 0.09mm, it should be 0.08mm +- 0.02mm. I prefer oh-so-slightly slack so I left that as is. The exhaust was at 0.10mm, it should be 0.12mm +- 0.02mm. As I prefer them oh-so-slightly slack I've loosened this up to 0.13mm.
The rocker cover gasket is leaking. I checked this out and the rubber has gone hard and cracked in the area near the spark plug, hence the leak. Considering the bike's age I think at 40k it would be rude to expect the rubber to be just fine. A cursory search of Ebay suggests a new one will cost me around £13 to £15. Pleasingly a genuine Honda one from a genuine Honda dealer is...about £8.50. Eeeee...I remember when Ebay wuz cheep.
All I need to do now is find a Honda dealer with one in...what are the chances?
Yip...they look OK to me...
Reader's Comments
Ren - The Ed said :-
My local Honda dealer doesn't have one in, but, they'll have one in for tomorrow. While slightly frustrating because I am impatient I think that's a pretty good show all in all. Thanks Wigan Honda.
01/01/2000 00:00:00 UTC
Ren - The Ed said :-
And the gasket was there for me first thing in the morning. I fitted the gasket outside the shop while receiving curious looks from the staff. I now have an engine that doesn't leak oil. This is a problem - how do I know if any oil is getting to the valves if it's not leaking? Dammit.
01/01/2000 00:00:00 UTC
Bob said :-
That's a cracking little engine - 40000 miles? Mind you I think you look after it better than your average spooty yoof.
You'll certainly know if oil ISN'T getting to the top end!
I've never had problems with tappets tightening, I usually adjust mine to the tight end of the tolerance because it makes the engine run quieter and I've had the misfortune to have bought a couple of bikes (sight unseen) where the camshaft and/or followers have had the surface broken up because the previous owner left the tappet gap to get wider and wider...
Still, I learn from mistakes and now I don't buy a 4T tiddler unless I've been and heard it running first.
It's fun fitting bike parts outside the shop. When I was studying for my HND in Wales I had a GP100, which had a damaged small end eye in the conrod. It would eat small end bearings every 2000 miles, I became a regular customer at a shop called "Everything but bikes" (that's what they sold) and would go in, buy the gaskets, bearing and circlip and fit it on the pavement outside! It was easy on the GP100 because the disk valve induction meant that there was only the exhaust and 4 head nuts to undo.
01/01/2000 00:00:00 UTC
Ren - The Ed said :-
Hey Bob. Yip my CBF receives fresh oil every 2000 miles without fail. It does get the occasional thrashing like riding into a strong headwind for 100 miles across Ireland but generally the engine is shown some mercy.
I'd ALWAYS assumed tappets went slack. However on the CBF 250 when I got it they were tight to the point where the was no gap at all. I suspect on both the 125 and the 250 the valve seats are cut such that they wear away quickly at first then once settled in the wear becomes minimal. Once the valve seats are settled then the rest of the system wears and eventually tappets slacken off. I'm finding very very little wear on either of them now.
2 strokes are a lot easier to work on at the top end. That said they're also noisy, smelly, unreliable and nasty things. I don't know if you noticed but I don't really like 2 strokes - hehe!
01/01/2000 00:00:00 UTC
Ian Soady said :-
"I'd ALWAYS assumed tappets went slack."
Some do some don't. On the Triumph 3 cylinder engines (the Hinckley ones anyway) they tend to close up*, and I think the same is true of many machines which use shim / bucket adjustment as these tend to wear minimally and the bigger problem is valve seat recession. Your 125 has a single camshaft with rockers so there are a lot of wear points - especially the rocker adjusting screw on the valve stem.
*Having said that, I checked my Tiger at the recommended 12,000 miles and all were within spec. A shame as I'd spent £40 on a special tool to change the shims..... Mind you I don't go wailing about at 10,000 rpm everywhere (or anywhere come to that).
01/01/2000 00:00:00 UTC
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