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450/500T Startup
AshimotoK0:
I got this from the new Vintage Honda Twins site from the 450K1 User handbook.
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MrDavo:
Interesting they are suggesting at the top of the page that you give it a few kicks with fuel and choke first, I’ve never done that.
The warmup makes sense, as it takes an age for oil to get up to the exhaust cam.
K2-K6:
For the manual text you've highlighted Ash, it looks as if they have lost some nuance in translation.
To me it means a fast idle by the first passage, with the second warning against a thrashing while outputing maximum torque. The two I feel are very different conditions for an engine.
Realistically, a cold start will always involve compromise in pure technical terms. In trying to normalize tokerances as heat comes up while attempting to keep the lightest load on the disparate collection of components will ordinarily place some risk in the event.
A fast (elevated) idle speed while running the least amount of fuel enrichment is the best route in my view.
Revs as an absolute are not the risk that's often projected, if compared to running rich on choke to keep it going at lowest revs while blipping it are ultimately far more detrimental, especially to the oil's condition as it very quickly dilutes with unburnt fuel byproduct. That of course will compromise the total lubrication all the period during which the engine is run.
The oil supply is ultimately linked to the crankshaft revolutions, making the cycles the cam experiences prior to full oil delivery mostly the same and not time dependent.
It doesn't look like camshaft wear comes from start routine though, most engines are broadly the same in crankshaft favoured primary oil supply building pressure first, subsequently the ancillary components follow.
the-chauffeur:
Ash - I've just found an old thread where you were pondering a roller bearing conversion on a 350 engine. Did you ever get anywhere with it?
I'm asking because I'm considering going the Cappellini route with a 450. I'm a little paranoid about the fragility of the exhaust cam and so along with the conversion kit I'm thinking about adding the oil filter kit, oil line and bored out/bigger oil pump piston mod. Yes, that's probably overkill for a road bike, and yeah I've probably got more money than sense . . . but given the lack of liquid cooling in the 450, I don't like riding in modern day city traffic on a bike designed for 1960's roads because of the stop/start nature of the journeys I do. I want to keep heat to a minimum and I suspect the rollers will help.
K2-K6 - would the fact that the 450 cams are suspended at height with no access to oil until it's forced round by the pump make any difference to lobe wear from start-up? In the case of the nearside exhaust lobe, received wisdom is that it can take anything up to 90 seconds for oil to get to that point from cold (I have no idea how true that claim is). Given the oil will also be at its thickest when cold and that's likely to reduce its spray coverage, that's gotta be tough on that lobe.
It's not a phenomenon that seems to happen much in other similar bikes and I'm wondering whether that's because most have oil baths immediately below the cam lobes that offer even very small amounts of lubrication until oil starts being pumped/sprayed about. Couple that with your theory about oil condition/contamination and I guess it's easy to see why the 450 exhaust cams fail so regularly.
AshimotoK0:
--- Quote from: the-chauffeur on July 08, 2020, 12:08:06 AM ---Ash - I've just found an old thread where you were pondering a roller bearing conversion on a 350 engine. Did you ever get anywhere with it?
I'm asking because I'm considering going the Cappellini route with a 450. I'm a little paranoid about the fragility of the exhaust cam and so along with the conversion kit I'm thinking about adding the oil filter kit, oil line and bored out/bigger oil pump piston mod. Yes, that's probably overkill for a road bike, and yeah I've probably got more money than sense . . . but given the lack of liquid cooling in the 450, I don't like riding in modern day city traffic on a bike designed for 1960's roads because of the stop/start nature of the journeys I do. I want to keep heat to a minimum and I suspect the rollers will help.
K2-K6 - would the fact that the 450 cams are suspended at height with no access to oil until it's forced round by the pump make any difference to lobe wear from start-up? In the case of the nearside exhaust lobe, received wisdom is that it can take anything up to 90 seconds for oil to get to that point from cold (I have no idea how true that claim is). Given the oil will also be at its thickest when cold and that's likely to reduce its spray coverage, that's gotta be tough on that lobe.
It's not a phenomenon that seems to happen much in other similar bikes and I'm wondering whether that's because most have oil baths immediately below the cam lobes that offer even very small amounts of lubrication until oil starts being pumped/sprayed about. Couple that with your theory about oil condition/contamination and I guess it's easy to see why the 450 exhaust cams fail so regularly.
--- End quote ---
Sorry I missed this last reply. The needle roller conversion was for a CB250/350K. I bought all of the bits but then acquired a stash of decent standard cam bearings so I sold all of the conversion parts to Pacre Racing...or for his mate anyway ...... remember him? Used to build Honda engines and sell parts until his place burned down and I think he's a pro. ballroom dancer now or something now :D
I think the best thing Capellini does for the cam problem is a re-designed baffle plate which somehow improves the oil retention in the area of the exhaust cam that's problematic. HondaTwins.net is pretty defunct now but there is a new forum called Vintage Honda twins and I am pretty sure a member there (ex-HondaTwins.net) has made his own version of what Cappelli does. cappellini one is expensive for what it is. I will try to find link of the forum guy who made his own.
http://www.cappellinimoto.it/catalog/motorbike/CL450/product/200
http://www.cappellinimoto.it/catalog/motorbike/CL450/product/201
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