Vento 350

[DewCatTea-Bob]

By: Muzz350
" The "Clymer" instructions did not seem logical and seemed to guarantee that I measured the clearance ramp in my V-timing readings but there it was in black and white so i thought I was missing something. "

____ I'm afraid that some readers of our last two posts may just shrug-their-shoulders at trying to fully-understand exactly what the deal is with what we're specifically trying to work-out...
__ You still haven't yet revealed what clearance-setting the Clymer-instructions direct that the valve-clearance must be reset to, for using the suggested ".1mm"/(.004") feeler-gauge size for taking the v.timing-readings with. _ The recommended clearance-settings (for each specific cam-model to be checked) certainly ought to be listed somewhere in their manual.
I was left to GUESS that IF the recommended-clearance was set at the same .1mm/(.004") amount, that then indeed the clearance-ramp would then of-course be included within the v.timing-reading, (which would certainly be misleading !).
However, I'd certainly expect for any such workshop-manual (like your Clymer-book) to specify a particular checking-clearance that's fairly larger than the feeler-gauge size which they suggest using for the valve-timing checking-job. _ So in this case, if a .1mm feeler-gauge is recommended to be employed for the job, then the checking-clearance ought to be set at (at least) .15mm/(.006"), (or whatever extra-amount the expected height of the clearance-ramp may actually be, for the particular camshaft being checked).
So certainly if Clymer suggests/recommends using the .1mm f.gauge-size, then they should ALSO recommend a PARTICULAR amount of checking-clearance (which the valve-clearance should be set to, for the job).


" I do like the rocker gripping the feeler gauge principle so increasing the clearance then inserting a feeler gauge which leaves the recommended clearance plus the clearance ramp is a very good idea. "

____ The "recommended clearance" (given in a manual) should ALREADY take-into-account the specific clearance-ramp (for the particular cam-model to be checked).
__ (It's my-own preference to use a thinner feeler-gauge, [than the .004" size],, it's exact thickness depending on the thickness-sizes of the available shim-caps which I happen to have to work with,, [adjusting the math/total to suit].)


Hopeful-Cheers,
-Bob

[Muzz350]

Hi Bob
Yes, the manual does list 10 models and all the clearances are more than the 0.1mm eg 250 GT in/ex 0.3mm.I assumed the list was the valve clearance for those models but it could be the valve clearance plus 0.1?
Muz

[Muzz350]

Hi Bob
Yes, the manual does list 10 models and all the clearances are more than the 0.1mm eg 250 GT in/ex 0.3mm.I assumed the list was the valve clearance for those models but it could be the valve clearance plus 0.1?
Muz

[DewCatTea-Bob]

" the manual does list 10 models and all the clearances are more than the 0.1mm eg 250 GT in/ex 0.3mm. "

____ Well "0.3mm" is near 12-thousandths -(.012"), and the GT's normal running-v.clearance is just .002 to .003", and-so that figure -("0.3mm") you've mentioned must be the particular clearance needed to check that cam.model's valve-timing.


" I assumed the list was the valve clearance for those models but it could be the valve clearance plus 0.1? "

____ Firstly,, the Clymer-manuals have been fairly well known to have printed an excess number of errors, and their listed-table of valve-clearance figures (actually for checking valve-timing) is one such (extra) notable error-case, as that particular table has been misleadingly mal.labeled (as NORMAL valve-clearance settings) !
__ Secondly, it should now be understood that the often mentioned "0.1" -(.1mm /.004") is not a common/standard-figure which always has to be involved with every (cam.model) case. _ As in the case of the "GT"/(Monza), the normal valve-clearance is actually only 1/4th of that supposed-difference (and not your supposed result of .008").
It may actually be a mystery of sorts as to exactly how Ducati decided how much extra leeway-clearance should be used for checking the valve-timing (of various cam.models), but-so I'm left to assume that the height of the clearance-ramp for the GT-cam.model is the .012" minus the thickness of whatever the corresponding recommended feeler-gauge is supposed to be, (which may not actually work-out 'fairly').


Dukaddy-DUKEs,
-Bob

[Muzz350]

Hi Bob & Jon
Re: 350
Is the spark plug type/heatrange critical?
• Bike Manual spec says – Bosch W225TI or Champion L-86 (now L86C)
• It had a NGK BR6 HS (R for racing) when I bought it. (Gap 0.7 to 0.8mm Haynes manual)
• I fitted an NGK Iridium BR6HIX =( I was Told 24 to 25 thou = 0.61 – 0.64mm gap ?)
(Points & coil ingnition)
Muz

[graeme]

I thought R was resister in NGK ? (BPR7HS is a protruding resistor)
The heat range is critical so it doesn't foul or burn too hot.
I found BP7HS best with our fuel and a 450, if that helps at all.
graeme

[Muzz350]

Thanks Graeme
I just checked the NGK site and it does say R = Resistor. Not sure where I got "race" from. I am not sure if a resistor type plug is good or bad?
Our fuel is pretty crap but we can get 92, 95 or 98 octane but how close it really is to those figures I don't know.
Do you also use 20/ 50 mineral based oil in your single? In my old bevel twin I always ran straight 50 weight oil.
Muz

[graeme]

Hi Muz,
I've been using castrol 20w50 for a long time in singles. Everyone has their preferences when it comes to oil.
Change it regularly and all is happy.
Our fuel isn't too bad compared to our US friends from what I've read.
My 450 likes BP, Caltex and Mobil is ok too but it fouls plugs very quickly with Shell.
The road 450 likes 98, and the RT with less compression likes 95.
If you have a resister in the plug cap as well as the r plug may not be good.
Some one knowledgeable may give a better answer I hope.

I can give you my carb settings but they are for 450's (29, 32, and 36) if this can help, but I doubt it will help for a 350?

Graeme

[Muzz350]

Hi Graeme
If you have carb settings for 32mm Dellortos that would be good to compare.
Here is the response I got from BP a while back re: my 1978 350. This was the opposite to what I had been told by a Ducati mechanic so as a Ducati owner your pactical experience is important for me to build upon. I would like to get it running the best it can before I change the cam.
Regards
Muz

Pre-1986 petrol engines in Australia were designed to operate with 98 Research Octane Fuels (the old leaded petrol) and so I would be using a petrol such as BP Ultimate unleaded petrol (98 RON minimum) as the standard petrol for this engine.

This would also satisfy the compression ratio (10:1) that you have quoted.
Typically, an anti-valve seat recession additive (AVSR) or lead replacement additive such as Valvemaster would also be added unless the engine has been rebuilt with hardened valve seats.
Regards,
Product Applications & Projects

BP Australia

[graeme]

Hi Muz,

RT 450 standard Desmo cam.
70/2 slide (I remove the pump actuating arm) I've had too much trouble with pumps to worry about them.
K6 needle, middle knotch.
AB 265
60 pilot
125 main, this depends on your muffler. Mine is baffled and fairly restrictive, a 122 might be better than the 125 that's in it now.?
Plug NGK BP7HS

Runs best on Caltex 95

Suggest you get the carb sorted before adding any lead replacement or upper cylinder lube as this can give false problems and make you think that something else is wrong. Use it sparingly if you must use it.

Hope this helps

Graeme