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Messages - BenPowell

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1
SOHC Singles & Twins / Re: CB350 1971 Restoration Project
« on: October 11, 2023, 07:39:59 PM »
Hi everyone,

More updates on the bike,

My V5 arrived last week only a few days after the inspection which was a nice surprise. So it’s now insured and ready for the road.

I took the bike out on Saturday for its first ride out, got a few miles down the road and started getting issues with misfiring and bogging down, which got worse the further I went.

I few things I have found is the charging system was a bit weak, but I’m getting good power from the stator, I’ve replaced the rectifier for a modern one which improved it slightly, but the thing that made the most difference was permanently wiring in the ‘night time coil, by connecting the wires in the headlight bucket, yellow wire into the white with yellow stripe. Thanks to Ash for that suggestion.
I now get a steady 13V at idle which is good.

But the bike was still running rough and misfiring on one cylinder (left side) so tonight I removed the point cover and ran the bike and the left side point contact is sparking continuously while the righ side had no sparking at all, so I think it’s time for a new condenser. Fingers crossed that sorts out the last of the running problems,

I checked the point the other day for sparking and could see nothing, got in the shed tonight where it’s darker and it was obvious straight away.

2
SOHC Singles & Twins / Re: CB350 1971 Restoration Project
« on: September 29, 2023, 11:03:31 PM »
Sounds like we are having identical issues Ben! My slow running jet just wont clear. It's been soaking in carb cleaner for 2 days. I've ordered a .35mm drill. As a back up, I've ordered some pattern jets (as genuine not available) as a back up. Also ordered some pattern floats.
Hopefully I'll have your success!

The radial holes on mine were all clear, but down the bore it actually goes to a smaller diameter and it was blocked there, I bought some 3D printer nozzle cleaners, turned out to be really useful for the carb, get a load in a pack for about 3 quid.

Link: https://www.amazon.co.uk/dp/B09L86LJ81?ref=ppx_pop_mob_ap_share

Was really quite tough to break through the blockage, and just for a final check I poured a small amount of petrol through to make sure the passages through the carb body were clear.





3
SOHC Singles & Twins / Re: CB350 1971 Restoration Project
« on: September 29, 2023, 10:13:17 PM »
Little update on the carbs tonight, I took them apart to inspect and found that the jet which is under the rubber bung (idle jet?) was blocked on both carbs. Must have missed it when I rebuilt them originally, because it took a fair bit of unblocking, gave everything else a thorough clean while they was apart.
Got them back on the bike with mixture screws 1 full turn out from loosely nipped up, and idle speed screws 3/4 turn from touch and the bike fired up straight away with no more popping from the right cylinder, in addition to this the idle mixture screws have a definite impact on the engine now, safe to say that was the issue there.

Before I removed the carbs I ran the bike with no air filters and could see the slides moving freely, and while off i checked the diaphragms and couldn’t see any holes, I also checked the slides and they are completely free, so I think the hanging rpm must have been caused by a lean running condition on one cylinder.

Tomorrow I’m going to spend some time getting the carbs set up, or as best I can without riding it.

Had the DVLA inspection this morning, guy was here 10 mins and took plenty of photos of the bike, hopefully I’m not waiting much longer for the V5, I just want to get out for a ride now  ;D

4
SOHC Singles & Twins / Re: CB350 1971 Restoration Project
« on: September 27, 2023, 07:25:34 PM »
Started up after actions taken in previous post - revs returning to idle better but still little response to slow running screw adjustment on R/H cylinder (and now no leak on intake manifolds) with misfire (pop) when slow speed screw backed out more than 1/2 turn. Should have checked that curcuit while I had the carbs off! I'll take the carbs off again and check the low speed curcuit for blockages - I'll feed any progress back Ben.
Also got a noisy tappit on R/H to sort when engine back to cold and strangely, the R/H silencer is far louder than the L/H (both new).

Thanks for the updates Phil, after adjusting the timing the other night and re-checking the valve clearances I can say it has made no difference to the popping except I now have a noisy valve which wasn’t before (shouldn’t have messed with them) pretty sure it’s just the one.

Checked for air leaks by spraying around the carb boots while running and that also made no difference to the RPM so it’s got to be something not right in the carbs, again mixture screws did nothing,

With regards to more noise from one silencer, to me that sounds like one cylinder is doing more work than the other, one of mine felt like it had a lower pressure from the exhaust so I increased the idle screw on that side and it brought it back inline.

I briefly unplugged the HT leads on each cylinder the one which was quieter cut the engine almost straight away, when i took the other off it continued  to run for a bit.

5
SOHC Singles & Twins / Re: CB350 1971 Restoration Project
« on: September 26, 2023, 10:37:59 PM »
Had a day on the 350. Rechecked all the settings - points bob on but timing (using the strobe) altered slightly, fiddled with carb setting and much improved but still intermittently hanging before settling to tickover. When I was building the engine on the bench and when fitting the carb manifolds, I thought the design of using JIS cross head screws and a gasket didn't seem a good design. The last thing I checked today was for air leaks on the carb manifold to head (using the carb cleaner method) and there was a clear movement in the revs when carb cleaner squirted at the joint.
Just spent the night stripping and re-assembled using a slight skim of silicon sealant and hexagon bolts.
I'll report back tomorrow
As an aside, its taken me back 50 odd years taking the tank off (when I had a 250k) and that bloody awful petrol balance pipe that goes from one side of the tank to the other under the frame - you have to juggle taking the tank off while trying to stop petrol coming out of both sides - its a bludy pain! I have put 2 tiny inline taps on the pipe (and disconnect the pipe in the middle between the taps) but there is so little space, its more trouble than the standard pipe.
Coincidence that Ash posted the same thing at the same time!

Sounds like you’re getting to the bottom of the issue, just out of curiosity when trying to set up did you find the mixture screws made no change to the running of the engine? While mine was idling I was messing with the screws on both carbs, but didn’t seem to do much. So I just left them about 1 turn out.

To me that sounds like something in the idle circuit is blocked, additionally the idle speed screws are quite far in to maintain a steady 1200rpm idle.

The tank balance tube is a pain, I left mine a little longer just so i can prop up the bottom of the tank for access without removing it fully, ideally 2 clamps and a straight connector in the middle of the balance tube would work nicely.

6
SOHC Singles & Twins / Re: CB350 1971 Restoration Project
« on: September 26, 2023, 10:27:20 PM »
I was only thinking earlier this evening if anyone has ever fitted 450 style CV carbs to a 350K and lo and behold this pops up on eBay ... a real mish-mash of an example.

https://www.ebay.co.uk/itm/386144812818

Ben ... did you try checking for inlet leaks with easy start sprayed onto the inlet stubs ... should have let me soften them with my magic fluid  ;D

(Attachment Link)

Will check for leaks tomorrow night, I hope it’s a leak, at least it’ll be fairly simple to do something with  ;D

7
SOHC Singles & Twins / Re: CB350 1971 Restoration Project
« on: September 26, 2023, 09:36:50 PM »
I’m fairly confident the diaphragms are fine, but they will be coming apart so won’t hurt to have another thorough check of them to be sure.

I do think it is a blockage somewhere, as I mentioned they were in a right state when I got them so in all honesty I’m surprised they work at all  ;D

Just need to keep chipping away to find the root cause, like I mentioned I’ve checked and adjusted points and valves, going to run the bike tomorrow night to see if that’s improved anything, while it’s running I’ll check for vacuum leaks.

If the problem still persists, the carbs will be coming off for another thorough clean. Really don’t think it’s anything too major though, the bike will idle nicely at 1200rpm rev freely (no engine load) just the odd pop from one the right cylinder.

8
SOHC Singles & Twins / Re: CB350 1971 Restoration Project
« on: September 26, 2023, 09:30:02 AM »
Had a go at settings on mine yesterday too Ben. Running awful really. Similar issues to yours. Balanced the carbs but slow to return to idle. Got good compression at 160 on both cylinders. Going to recheck all settings, check for inlet leaks.
I'll report back too if any progress

Sent from my moto g(50) using Tapatalk

Mine sometimes hangs at around 3/4K rpm. Only occasionally though, most times it returns to idle quickly, but a quick blip of the throttle returns it back to idle, sticking slide maybe?

Frustrating thing is I would have liked to work on the carbs this week but with the inspection on Friday it’s probably best to leave the bike fairly complete. I’ll have most of the weekend to work on them and try making changes, I will try to make one or two changes at a time to narrow down the issue.
I will investigate for air leaks probably Wednesday/Thursday since I can do that with the bike together. And also run it to see if the timing/valve adjustment has had any effect.

Bu yeah please keep updating, no doubt we won’t be the first or last to have these issues, on other forums posts aren’t followed up with results so become a bit difficult to pin point potential problem areas.

9
SOHC Singles & Twins / Re: CB350 1971 Restoration Project
« on: September 25, 2023, 11:28:09 PM »
Bit of a follow up from my last few posts.

Clutch drag - after running the engine for a while and getting some heat into the oil seems to have solved the issue, still feels like it has a fair bit of drag when the oil is cold compared to being hot, but seems to work okay. I think it will probably improve further once it’s had some use.

Carbs - my float height was incorrect causing a really rich mixture, for the 3D carbs the float height needs to be 26mm, I initially set this at 21mm as per some manual but obviously it differs depending which carbs are fitted, I was able to get the bike idling nicely and had it moving under it’s own power for the first time, which felt like a bit of an achievement. I still think the carbs need some more work the left cylinder seems to run fine, but the right seems to pop/backfire down the exhaust when letting off the throttle, I think it is probably running a bit lean based on the spark plug colour. Will need to check for vacuum leaks.

I rechecked points and valve clearances tonight, checked the auto advance functions freely. Will probably get the carbs off Wednesday for another clean I suspect the idle passage is blocked slightly.

Will report back if popping and banging from right side eventually stops,

V5 Application - got a letter in the post today from the DVLA, turned out to be a request for a vehicle inspection, just my look. Anyway they’re coming in Friday to look at the bike, hopefully shouldn’t be much longer till I get the V5.

10
SOHC Singles & Twins / Re: CB350 1971 Restoration Project
« on: September 12, 2023, 09:30:44 PM »
I'm at the carb tuning stage with my 350 Ben (next week as going away till next week) - tuning seems basic. Have a look at page 60 in the workshop manual (in Ash's dropbox)
My clutch was dragging a bit too but not test rode it yet - have adjusted most of the drag using the screw and nut adjustment.
I think Ash may be the man to ask!

Let me know how you get on with yours when you get round to it, I read the book and agree it sounds straight forward. My carbs were in a bit of a state when before I cleaned them up so could be something else, just don’t know what.

11
SOHC Singles & Twins / Re: CB350 1971 Restoration Project
« on: September 12, 2023, 09:27:48 PM »
Clutch action does not sound right, clutches can stick when left unused for several months but not every time.

Might be your clutch cable is sticking.


It’s a strange one, I assumed it was because it had been stood for a long while, but I took the side cover off the engine and you can see the clutch disengaging, but the individual plates stick, it’s like how two really flat surfaces put together will grab.

It may improve once it’s had some heat through it and been bedded back in. Can only try I suppose

12
SOHC Singles & Twins / Re: CB350 1971 Restoration Project
« on: September 12, 2023, 06:36:10 PM »
Hi everyone,

Bit of an update but also in need of some advice.

Finally, the engine was fired up on the 350 and managed to get it to run for a little on the choke but that was about it. I ended up taking to carbs off and found one of the floats filled with petrol so hopefully that’s the only issue. I had checked the floats a while back and they seemed okay.

While it was running i was trying to adjust the mixture screw and it didn’t really seem to have much of an impact. So not too sure what the issue there is? Air leak maybe?

Next thing is the clutch seems to stick together, so tonight I removed the plates soaked them and re-assembled, the clutch disengages when the lever is pulled but the plates are sucking themselves together, and take a shock to release them. Is that normal or should you be able to pull the clutch and turn the back wheel by hand freely?

Other than that though the bike is pretty much compete and I’m currently waiting for my V5 to arrive in the post, I’ve also passed my test now so as soon as it’s done I can get it insured and go for a ride

Cheers everyone,

13
After the the CB350K2 for one year only Honda did the K3 model (and 250 version in  the UK in Candy Gold only). On the USA 350K3 they ditched the silver base-coat on the Candy Ruby Red and used white base-coat with Candy Ruby Red. Ben Powell is painting his 71 K3 import in this scheme and it looks stunning. If anyone says Honda never did this, well I am sorry to disagree but you are 100% wrong.

I have just finished painting side panels, fork shrouds and headlight cowl, picture of one of the panels below, chuffed to say the least.

Looks like a good turn out at Crich, might make it there myself next year😁
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14
SOHC Singles & Twins / Re: CB350 1971 Restoration Project
« on: June 02, 2023, 08:58:59 AM »
I tried all sorts of solid reds including the stuff that RS sells but it didn't have the 'hard to describe' glorious finish of the NOS  Light Ruby Red part I have.

One for example was a modern red paint which in other forums is regarded a close match for the light ruby red, but honestly it just didn’t have the same depth of colour. To be quite honest, it looked dull and flat, as you would expect from a solid colour paint.

Honda were well into solid colours in 1971 so why experiment with candy over white base when they could just have used a close match solid colour.
It was obviously a problematic finish for Honda (or their sub contractor) because my tank was definitely original and had been painted 3 times ( posted a pic earlier).

The CB350K in Light Ruby Red  never sold in the UK. All of the imports are sun faded 52 year old paint finishes , So it is difficult for anyone in the UK to appreciate the deep rich original finish.

The candy top coat I used is Max Meyer M277 (a modern Honda colour, which is normally used with its associated deep-gold M277 pearl base-coat.

I also tried seven different engine enamels in silver that Ash loaned me and decided on the Dupli-Color DE1615 stuff as it was the closest match I could find to the original factory finish. It's temperature spec will not be a problem because the head and barrels are unpainted on my model (and also the lower half of the crankcase).

15
SOHC Singles & Twins / Re: CB350 1971 Restoration Project
« on: May 31, 2023, 08:49:29 AM »
Read your whole project post again - very interesting rebuild - my heart sank when I saw the camshaft bearing worn oval.

How did you fix that in the end ?

Yeah the camshaft bearing was really bad, considering the condition of the rest of the engine I wouldn’t have expected that, in the end I managed to get hold of a NOS cam bearing, failing that i was going to bore it out and machine a bush. I think it could be done fairly easily, unfortunately I don’t have access to a lathe anymore since I’ve moved jobs, I would like my own lathe at some point and I’ve kept the old bearing so might get chance to have a go in the future, just to see how feasible it is.

So is the bearing separate from the cam cover - lucky to find a NOS part.

No, its one part, the camshaft sits directly in the housing, so I would have to over bore it, then use use some material to make a sleeve to reproduce the original bore size, would need to be suitably locked in place, but should be fine to do.

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