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Topics - Oggers

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1
SOHC Singles & Twins / Decompressor cable 250RS 1980
« on: March 06, 2023, 01:52:36 PM »
Any ideas where I may find a decompressor cable for the 250RS? Looks Like Dave Silver cannot supply.....

Will any other cable from any other bike fit?

2
SOHC Singles & Twins / Detecting clutch slip via kickstart
« on: May 19, 2022, 04:31:57 PM »
Gents

I neeed to know when the clutch is just slipping. You can do this with the kickstart, and clearly if the clutch is slipping badly then on kickstart there will be no turning of the engine! However, I want to discern when it is just starting to slip using the kickstart - what are the symptoms please?

Cheers

3
CB750 / Hesitation after @ 4500 rpm
« on: April 24, 2022, 04:00:10 PM »
Not a Honda - but I feel you gents may be able to point me in right direction as the solution may be similar for CBs . I have another bike - 78 Kawasaki KZ650 - which has performed wonderfully since restoration a year or so ago. I took it out on Friday and it ran beautifully. Saturday took it out on another spin, but this time filled it up with super unleaded as normal. After that, bike rans fine until you give it some throttle at @ 4500 rpm and it hesitates - somewhat alarmingly lurching as it does so. It tries to go, but hestitates again. Very erratic, very hesistant, will not go above 4500. Below 4500 it seems OK - ish....

Clearly I have though about rubbish in the tank being disturbed when filling up, and then finding its way to the carbs. I took the tank filter off - very clean, and the extra in-line filter between petcock and carbs looks fine and clean. Cleaned plugs - all OK, checked gap - OK, cleaned air screw needles - all OK, fuel line blown through, vacuum take off to petcock is OK, Auto advance lubed up, all seems free moving.

Taking the carbs off and cleaning jets etc. is a royal pain. Has anyone got any other suggestions that I could easily do, and do you feel I am on the right track with the root cause? - rubbish in the carbs bascially. Deeply annoying after it was running so well!

4
SOHC Singles & Twins / Lubrication
« on: April 20, 2022, 11:16:01 AM »
Staedy progress rebuilding the bottom end. New balancer chain on - thanks Oddjob - various seals replaced, crankcases given new coat of paint etc etc.

Both crankcase covers are now also on in preparartion for top end rebuild. However, I did not lube up the new balancer chain before fitting the right hand cover. Does this matter? - as I assume as soon as bike starts up, oil will start thrashing about over the chain anyways?

5
SOHC Singles & Twins / Primer with PJ1
« on: March 30, 2022, 10:53:21 AM »
One for Dave maybe....

Can you apply PJ1 onto bare metal? As per previous post, I was thinking of applying a HT (etch?) primer beforehand, but is this truly necessary? What have others done to recoat bare metal barrel/head/cover please?

6
SOHC Singles & Twins / HT primer
« on: March 27, 2022, 04:42:09 PM »
I have now taken the upper crankcase case back to bare metal. Do I need high temp primer or will UPol or similar etch primer suffice? I have the PJ1 for the head, barrel and cover and perhaps thinking of using it for the upper crankcase also, but wouldn't mind using an etch primer as it is now bare metal.

Thoughts welcome.

Incidentally for the top end bits, I was thinking of vapour blasting back to bare metal then high temp (etch) primer, then PJ1. Bit nervous about the beads in the vapour blasting becoming entrained somewhere - a thorough clean I suppose?

   

7
SOHC Singles & Twins / Balancer chain
« on: March 22, 2022, 02:18:35 PM »
Right - I fear I may rock the boat here! I have ordered a new DID balancer (kart) chain and a split link for it. I fully realize that I perhaps ought to use a rivet link, but several problems.

I am not confident or practiced enough to mushroom out a rivet link correctly.
I don't have the right tool.
No-one around here can seemingly do it for me - despite several attempts with the local bike shops.

So, am I asking for trouble using a split link in lieu of a rivet link?

My thinking

Not much torque on a balancer chain - it's not like a drive chain.
Relatively small chain.
Cam chains operate in a similar way, and I have seen cam chains with split links.

Thoughts welcome as ever.

8
SOHC Singles & Twins / CB250RS progress
« on: March 22, 2022, 09:53:44 AM »
Things moving nicely. Crankcase halves now split - and no I did not need to remove the clutch. It all "looks" OK in there so I think this is where I will stop engine disassembly. Pic attached. I will though replace the large oil seal behind the drive sprocket and any other seals I currently have in the spares box. 

A few further Qs if I may

Anything else I should at least check whilst at this stage?
Balance chain - now off and awaiting replacement - thanks Dave. Fitting a rivet link - Do I use a rivet tool to deform the hollow pins so they hold the link in place, or is there another method?
I cannot see any discernible gasket material at the mating surface of the halves. Would it be wise to use some - Hondabond?
Ref. refitting the balance chain - I have only pulled off the front balancer weight and noted the marks. Is it then a case of aligning the painted links with the marks on all 3 sprockets and then refitting the front balance weight?

Frame is really nice after a clean. Like new!

Many thanks again

9
SOHC Singles & Twins / Timing
« on: March 15, 2022, 02:42:13 PM »
Somebody wake my brain up please! On the 250RS and doubtless many others, I believe valve timing is basically achieved by lining up the marks on the cam sprocket and the head with lobes at 8 and 4 o clock when crank is at the T mark.

However, there could be 2 feasible positions for the crank at the T for this eventuality. Does it matter? Ignition Timing could be 180 deg out - or could it? If not, why not?

10
SOHC Singles & Twins / Honda CB250RS pic and questions please
« on: March 14, 2022, 02:56:01 PM »
Chaps

Managed to take a photo of my new steed. A 1980 CB250RS in very decent nick - well on the outside anyways. Hopefully an attachment at the end of the post.... Nice round headlamp - which I actually prefer, and I may even replace the square indicators with round to match....such heresy!

It is now all apart, engine out, head and barrel off, and now awaits my tender mercies to replace worn bits with the myriad of spares that came with it. Good news is that rockers, cam lobes and bore all look OK. Nothing too shocking I don't think. I'll just replace things as I go....A  few Qs if I may

I have a camshaft sprocket and a new cam chain. it would seem sensible to replace them along with the crankshaft sprocket. Any clues as to how to pull off and replace the latter woiuld be appreciated. Haynes manual is a bit vague.

I actually have new IN and EX rockers in my pile of bits. Given Dave's troubles with the locating pins I wonder if it is worth replacing them? The existing ones look fine.

I also have both new final drive sprockets, but no new final drive chain. Dave Silver I guess, anywhere else?

Whilst the engine is in bits, is there anything else worth checking or replacing? I'll look at the balancer chain.

I also have a new piston and rings. Is is worth replacing the existing with these?

Many thanks

Mark


 





 

11
SOHC Singles & Twins / CB250RS info please
« on: February 24, 2022, 11:28:07 AM »
Folks

Thinking about  buying a 1981 (kisckstart only) CB250RS to recapture those heady days of my youth when I had one for a while. At the time, I thought it was a very good bike, but I never really took it apart to any great extent. The one I now have in mind has about 30K on the clock so I wouldn't mind delving into the innards of the engine to check things out. With that in mind, a few Qs if I may

How easy - or difficult! - is it to start exploring the innards of the engine. Is there anything in particular I need to be aware of?
What would you recommond replacing given the mileage - main bearings? crankshaft bearings? piston rings? cam chain? valve guides?
Anything else on the bike I should be mindful of?
   
Many thanks

Mark

12
CB350/400 / Static timing 76 400/4
« on: August 14, 2020, 11:03:50 AM »
Folks

Retiming the bike. Not completely happy with it as it seems to hesistate a tad in lower/mid range. Could be something else of course, but for now let's eliminate the timing.

Still not got round to purchasing a strobe, so static will do for now. My basic procedure is as follows

Align F mark for 1 and 4
Ignition on
Voltmeter across 1 and 4 contact terminal and earth
Turn plate slowly, and as soon as you see battery voltage, lock the plate off.
Repeat for 2 and 3

A few points.... pun intended

Once battery voltage shows, is this the point where you lock off? is there any recommendation to advance or retard it a little from this point. If so, by how much?

Points gap as per the book says 0.3/0.4mm. Seeems quite wide...Do we go with this?

All plugs were quite sooty- Could be the timing was out, I have given the carbs a good spray with carb cleaner and advance mechanism looked fine. New air filter ordered. Anything else it could be? Plugs themselves perhaps?


13
CB350/400 / Choke
« on: May 29, 2020, 05:05:49 PM »
Folks

76 400/4 running and handling well. One minor issue - well hopefully minor. Choke lever on the nearside is connected to the (common) choke flaps by a length of bent rod with a collar and grub screw. The issue is that the choke flap spring works to pull the choke flaps closed. When the choke lever is actuated to the open position - fully forward and  normal running - there does not appear to be adequate sticktion - for want of better words - to hold the choke flaps open against the spring. What happens is the choke closes itself when the bike is ridden, and will not stay in the open position. Result is a rich running bike and 3000 rpm on tickover!  - unless I push the choke lever forward again.

As an aside- if I disconnect the rod from the choke flaps, the lever moves freely and fully forward

Am I missing something blindingly obvious here?   

14
CB350/400 / Air intake manifold
« on: May 04, 2020, 09:27:47 AM »
Spent most of Saturday fighting to get the black plastic air intake manifold back onto to the rear carb stubs, and sad to report the manifold probabaly won. It is nearly correctly seated on the outer stubs, but certainly not on the inners. I'd say @ 5mm gap until it butts up.

Essentially I removed the blessed thing when refurbishing the bike. It was difficult to remove and I half expected it to be pig, but not that much! Intially I lubricated each carb stub and dunked the entire manifold in hot water to soften the plastic - no joy. Was not going on at all. Dressed off the innner bores of the manifold stubs a little - still no joy, then wrapped some abrasive papaer round a drill bit and took to the inner bores again removing more plastic. Smoothed it all off, lined up the dots, and tried again - better but not much, but at least it is on!

Some observations. The inner bore of the air manifold stubs appeared to be tapered not parallel. This is surely not conducive to clamping to the carb with the jubilee clip?  It cannot provide much of a clamping surface, and will have a tendency to slip off when the clip is tightened - which it did.

The collector - the large plastic box of most of the manifold is of course not rigid at all. Doesn't help when trying to push the inners onto the carb stubs. It just deforms rather than pushing the inners onto the carbs - hopeless!

Removing material from the inner bores means the wall thicknes is reduced, which means the jubilee clips "bottom out" for want of better words. I just got enough purchase to get them to clamp the manifold intakes properly onto the carb stubs.     

Tips for next time much appreciated - Can you fit the air intake manifold before offerring the carbs up to the head I wonder?   

15
CB350/400 / Ignition - or lack of!
« on: April 16, 2020, 09:35:19 PM »
Right- this blinking bike is doing my nut  >:(

Finally after epic wiring problems, new regulator fitted and all wired up. Sprung into life first kick - Hooray. All sounded fine. So, as we are all bound to do, I did the usual cursory checks after buying a new (to me) bike. Tappets - fine, clean plugs- fine, clean points- fine, check points gap - fine. All good.

Reading about on this forum, time to do a bit of static timing - before I think of buying a strobe and doing the dynamic. Consult Haynes manual. Off with the blue capacitor wire for 1.4 cyl. Test lamp between Earth and breaker terminal, Ignition on. Turn the shaft, test lamp lights more or less at the right point, but I also noted quite a bright white glow at the points. This did not seem good. Lamp was disconnected and capacitor rewired as it was originally. Tested votage across battery with ignition off - 7V and seems to be charging! Very odd. Tried to start bike - no chance. Tested voltage across battery with ignition on - 3.5 V. No spark at points when gap is flicked open either! All fuses good by the by.

So - have I somehow goosed the capacitors? No idea how as  I was very careful to follow Haynes instructions. If so, can I get replacements easily enough?

All deeply frustrating - especially as I had it running quite nicely! >:( >:( >:(!

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