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Messages - 400 Cafe Racer
16
« on: October 01, 2022, 04:37:55 PM »
Was following a Triumph 900 the other week coming back from an oil meet. It started to smoke, I could smell oil being burnt. I signaled him to pull over and his left leg up to the knee was saturated in oil, it was pouring out of the engine and forming a pool on the floor. He'd only had the bike a month so he was understandably a little upset. Turns out one of the half moon shaped rubbers sealing the camcover to the head, where the cams would be, had popped out. We managed to force it back in enough that he could get home.
The next week he turns up and explains the breather pipe had been fitted wrong by the PO and instead of being fed to the bottom of the airbox they'd fitted it to a blank on the airbox. This compressed the cases so much the seal popped out.
This got me wondering, could the engine be forcing oil back into the airfilter via the recycling system fitted to the 400, this causes the smoke from the exhaust. Which leads you to think it must be head related when in fact it could be something else, like a failed ring allowing compression into the crankcase.
Have you checked the airfilter to see if it looks really wet with oil?
Also check the accuracy of the breather pipe inner diameter to ensure fully unrestricted breathing over the full length. Some of these breather pipes can Kink or partly deform which could lead to choked breathing, crankcase pressure build up and force thin hot oil past the valve stems and piston rings.
17
« on: July 13, 2022, 07:48:45 PM »
Yes, you can rince it out with any oil and it will have a slight beneficial effect. No idea if the 350F aftermarket 4 into 4's are any good but unless you're riding it every day doing 12,000 miles a year, I wouldn't worry about it to much. The worse thing you can do is keep starting the bike up, creating condensation and then not running the bike for long enough to dry the condensation out. That's the main killer for the exhausts.
Hi 350 Simon, +1 to what Nurse Julie says. If you have a small bleed hole in the silencer clamp you will be amazed how much condensation water comes out within the first minute of starting. Probably a good egg cup full at least. It tends to get trapped where the 4 pipes meet together. Give the bike a proper run and warm up to ensure that the full system is hot and will evaporate any moisture/water.
18
« on: July 12, 2022, 09:29:05 PM »
So, couple months (and just a few kilometers, really) later. I'm back at square one.
Again, Cilinder 2 is smokey. I started riding, nice and easy. No smoke. Once everything was nice and up to temp I gave the ol'girl the beans and cilinder 2 (I have a non-balanced 4-4 exhaust, so easy to diagnose) started smoking again. Looks like head gasket again.
I'm going to retorque the head again, first without changing the gasket. Remember last time I found 'loose' head nuts.
Could there be anything wrong with my Studs, or Head?
Is there any harm in using an extra ring under the head nuts, just to make sure the nuts are not bottoming out on the studs (because of the aforementioned elasticity)?
I started riding, nice and easy. No smoke. Once everything was nice and up to temp I gave the ol'girl the beans and cilinder 2 (I have a non-balanced 4-4 exhaust, so easy to diagnose) started smoking again. Looks like head gasket again. Hi Erwin, There may be some oil overheating/thinning occuring, which will promote oil burning. If you have a 466 bored out engine you would be running hotter than normal and definitely need oil cooling. On a standard engine you will maintain about 90 to 105 degrees C oil temp with normal riding - give it the beans and you will soon be up to 120 C, with oil thinning. I think this causes oil degradation and probably why Honda specified 1500 miles oil changes. Just another factor to consider. FWIW Dennis
19
« on: June 24, 2022, 05:13:28 PM »
I presently have a small digital voltmeter mounted on the handlebars between the mounting brackets.
It works just fine but in bright daylight you can't read the display.
Has anyone here fitted a small diameter Analogue guage -the old headlamp mounted units would be ideal you could fit a raised type unit in a suitable housing?
Hi Ted, In terms of positioning I think it’s down to personal choice. If you look at my “Cockpit Upgrade” post you will see I accommodated 6 gauges. The AFR gauge was a little lager in diameter so would not sit as low as the others. In terms of housings it depends what you can create with the garage resources you have available. I am pleased with the good info that mine provide, and the wiring you have should work fine, but I would go for a gauge that has a damped movement, to avoid needle vibration. Hope this helps. Great that you are now on the road. All the best Dennis
20
« on: June 03, 2022, 04:23:08 PM »
You can't rush a 74 Yr old body that's already doing it's best to heal ASAP.
Hi Ted, Just a catch up. Hope you are soon sorted mate, up and running, firing on all cylinders !! All the best Dennis
21
« on: June 03, 2022, 04:15:12 PM »
Hi sc29, That idle performnce sounds very erratic to me, more like 2 to 3 cylinders doing the work rather than 4. This would cause an oscillation effect on the crank speed and aggravate both timing chain and clutch assembly. (A bit like shaking a tin full of nuts and bolts, rather than just carrying them carefully) As NJ says, its best to go through all your core settings, ign timing, tappets etc, etc, then make sure the carbs are syncronised correctly, and mixtures correct so that all cylinders are doing equal work at idle. This will smoothen out tickover and make for cleaner performance throughout the range. Just my observations. Let us know how you get on.  Dennis
22
« on: February 26, 2022, 07:27:34 PM »
Great stuff Ted, Look forward to the launch, with all the love and care you have given her I am sure she will run like a clock after the usual Carb adjustments after initial settling in. Cheers  Dennis
23
« on: February 26, 2022, 06:33:25 PM »
Thanks Julie mine is not like that it's just a button like the starter.
Hi Ted, Mine is the same as Julie's with the headlamp flasher, they have matching faded patina at the edges and look original. My bike is UK registered in 79 and late F2. It seems you are well into the wiring now, when is launch day Ted ? All the best Dennis
24
« on: January 28, 2022, 09:43:19 PM »
Do you think it’s ok to torque it up to the level the manual says, or is that too tight?
Also - think canister filters doing the same job - only hand tight with no tools, as Bryan says, just nipped tight is all it takes if the "O" rings are all good.
25
« on: January 16, 2022, 04:09:02 PM »
Just to report back I seem to have cured the problem - I took the carb bodies to work and gave them a good blast with compressed air, fitted the new seals, and reset the float heights. So one (or a combination?) of these made the difference - my gut feeling is the float heights were the culprit.
Thanks Alex and everyone, hopefully I won't need to take those carbs off again anytime soon!
Hi Alex, Pleased it was straight forward to find and that you got it fixed .  All the best Dennis
26
« on: January 12, 2022, 02:32:49 PM »
On my 400F the air filters and exhaust are non standard and I have an Innovate Air / Fuel Ratio guage already fitted which was very useful during re-jetting and setting up under actual running conditions on the road. The settings I have used are to deliver best power, torque and engine temperature, with no specific regard to economy or plug colour.
Dennis, I'd be interested to hear how the Air/Fuel physically fits on a 4 cylinder 4 carb bike? [/quote] Hi Phil, To avoid distraction from Alexs' post I have put a link to my post showng recent guage additions. I have just added a final one to show where the sensor is fitted in the intermediate pipe. Dennis http://www.sohc.co.uk/index.php/topic,26987.0.html
27
« on: January 11, 2022, 03:35:07 PM »
Hey Dennis, thanks for all that sweet sweet info, I think I will do the vacuum gauge sync next time working on the bike. Seems like it will clear up more questions and hopefully solve my issues.
I was actually wondering if there is a proper methodology for the mixture screw settings. I know that the look of the plugs is a telltale sign but I was wondering how precise it gets without requiring an IR exhaust gas probe.
Cheers!
Hi thanks Alex, you are welcome, I would say that the if your bike is standard spec regarding air intake, air filter design and exhaust system, that the standard procedures and guides documented for carb settings are the best to use. The plug colour can be a useful guide for normal settings. In any event the matching of equal slide heights from idle to full throttle is desireable to ensure equal fuel/air volume to all cylinders and in theory deliver equal power from each cylinder. There inevitably could be small variations on position of the idle mixture screw position between individual cylinders for final setting, due to small variations in manufacture. This is fundamental to all tuning. On my 400F the air filters and exhaust are non standard and I have an Innovate Air / Fuel Ratio guage already fitted which was very useful during re-jetting and setting up under actual running conditions on the road. The settings I have used are to deliver best power, torque and engine temperature, with no specific regard to economy or plug colour. I have assumed that all is OK with the Ignition advance unit and that if you have standard ignition, that all your contact breaker points, condensers and other factors are correct. As Ted has hinted, its worth checking that all is OK with the static timing and centrifugal advance unit. Look for anything that could cause variation. Seized or stiff action on the spindle or weights, preload on the springs with no looseness, correct full advance as Bryan says at 2500 RPM I am sure with patience and perseverence you will nail the problem - and keep us up to date with how you get on. Dennis
28
« on: January 10, 2022, 06:44:08 PM »
> only because I buy things I don't need , don't want and don't know what to do with
It's the only way 
Indeed 😂😂😂😂😂😂
Hi Julie, Could you be missing Hettie ?? Good luck. Dennis
29
« on: January 10, 2022, 06:22:27 PM »
Hey Alan,
I guess that could be possible with old cables. As it gets old with many manipulations and service the copper wires can fray and cut which could lead to intermittent connections.
I have never encountered the case in motorcycles or cars or else but I have in houses and offices with old electric installations.
Soo maybe?
Hi Allan and Alex, To the best of my knowledge the spark performance on each coil provides for simultaneous sparking on both cylinders served by the coil - ie 1 + 4 for one coil and 2 + 3 for the other coil. This means in fact that the cyinder that is not on compresion stroke has the spark "wasted". Unless there is a specific problem with one HT lead or cap, the spark performance should be the same. My comments below assume that there are no carb or inlet manifold air leaks.
Having looked at the issue you have got Alex, I encounted a similar situation during tuning my carbs after doing only a bench sync. I found that spending time afterwards with close attention on the vacuum guage balancing and mixture sync method, this unevenness and surge disappeared. It only needs one of the cylinders not contributing equally to the tick over, and a little off with the mixture to cause this. When the off cylinder decides to clear a little and then "comes in and contributes", this causes a rise in engine revs for no apparent reason. You will be supprised when making adjustment with the vacuum guage, even - say 5 degrees - rotation of the balance screw for 1 cylinder will make a big difference to all the other cylinders. Just keep repeating the sequence until they are all the same. Hope this helps. Dennis PS Just thought I would add a small note to explain that for example in the same period (1970 - 1980 )that with a 6 cylinder car engine with 2 or 3 Carbs, to overcome a tendency for imbalance on idling the manufacturer would tend to put a small balance pipe connected across the manifolds so that all cylinders could suck Air/Fuel mixture, even though the individual Carbs may not be set spot-on. In the case of the 400F all manifols are individual and have NO interconnecting balance pipe, so this makes the correct balancing and mixture for each Carb and Cylinder hyper critical to get best running and performance.
30
« on: December 14, 2021, 04:53:16 PM »
Yes take care and get well soon. The down time will give you opportunity to think up some more fab engineering to wow us all with!
My sentiments exactly X2All the best Dennis
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