Vento 350

[machten]

If you made the main a 122 those would be the factory specs for a PHF32 on an individual cylinder of an 860 GT/860 GTS/900 GTS. Probably no surprises there that that works ok

Kev

[Muzz350]

Hi Jon
I have ordered the parts to replace the double coil springs in the Vento with standard hairpin springs the same as you have done.
HI Graeme.
Got rid of the resistor plug and the bike idles better especially noticable with the carbi adjusted for a slow idle. Plug colour looks good also.The sooty appearance has gone.
I feel I am making progress.
(Got lost when I tried to save this post as a draft. When I went back and completed it I couldn't figure out how to post it?)

Muz
Also , what is the difference between Post and "quote" ?

[DewCatTea-Bob]

" I have ordered the parts to replace the double coil springs in the Vento with standard hairpin springs "

____ What is the reasoning for bothering to do that valve-spring replacement-job ?
The outer coil-springs alone (as also [but solely] employed by the 750/860 L-twins) would be sufficient-enough for any milder cam-model you may install.




" what is the difference between Post and "quote" ? "

____ I'm glad you've brought this up, (cuz I also think others are-not quite aware of exactly what's-what on this matter).
__ When ya choose to place your very-own posting in-line at the end of an existing 'thread' simply because ya wish to merely add a post with just your-own thoughts concerning the particular 'topic' of the thread itself, then in THAT case, ya click on the button (at the bottom of the thread) that's labeled: ' POST REPLY ' .
__ In the OTHER case however, when ya rather choose to instead click-on the button labeled: ' QUOTE ' , (which is located at the upper-right of EVERY posted posting), then in THIS case, your intended post will ALSO include the established post that's seen on the same part of the thread-page as where the QUOTE-button -(which ya happen to chose to click-on & make use of), is located.
The included (already established) post will automatically be placed within a shaded -(high-lighted) area which will be placed above and along-with your-own (normally-presented) post-wording.
THIS manor of adding your-own post, is the expected method which ought to be chosen when ya wish to specifically respond to something that's been stated within the particular post of which you've clicked-on IT'S-own QUOTE-button, (rather than when ya merely wish to simply contribute your very-own original thoughts, to be posted to the general posting-line of the thread).
__ So bottom-line,, simply use the 'POST REPLY' button to merely add your-own independent thoughts, posted to address the general thread-topic,,
OR, on-the-other-hand,,
use the 'QUOTE' button to specifically address anything in particular within the chosen posting (which has inspired ya to place YOUR post), either in simple/mere 'response', or a purposeful DIRECT-reply* .
(* By "DIRECT-reply", this means that ya wish to specifically [or at least more-so] address the particular member who wrote the post [of-which you've chosen to "QUOTE"],, whereas otherwise, if ya rather-instead merely wish to just 'quote' posted-wording as a springboard for your-own INSPIRED-thoughts, then that's what is meant by mere "response".)
____ If I've not covered some minor aspect concerning this (somewhat fairly confusing) issue, then please ask for further clarification. _ (Even if ya-yourself don't personally care but suspect that anyone-else may still benefit from any further detailing on any left-out related aspect.)


Hopeful-Cheers,
-Bob

[Muzz350]

Hi Bob.
Trying out the" Quote" button

____ What is the reasoning for bothering to do that valve-spring replacement-job ?
The outer coil-springs alone (as also [but solely] employed by the 750/860 L-twins) would be sufficient-enough for any milder cam-model you may install.

I visited an old friend who has built race engines for about 40yrs (and had a couple of the Spanish engines sitting in his shed) and he suggested a set up from his experience that would handle the 40mm inlet valve and the Spanish cam.
Also, Jon Pegler has changed his coil spring and is happy with the result.
Muz

[DewCatTea-Bob]

" Trying out the" Quote" button "

____ Okay, then when you did, you should've noticed that my ENTIRE post was captured & highlighted,, and since that's obviously now not the resulting-case, then you must've next stepped-onward & edited-out other than only what you wanted to be left-remaining, (plus that which would've caused my posted-wording to become highlighted).



" he suggested a set up from his experience that would handle the 40mm inlet valve and the Spanish cam. "

____ By "Spanish cam", I assume you're meaning the stock (extra wild) Vento/Lento-camshaft ?
If so, then here is why I'd advise against any weakening of the Vento's stock valve-spring setup...
The stock Vento-cam is so wild that it's of very little use at lower RPMs, than near red-line,, so to make good-use of that cam, you need to keep the engine running near the highest RPMs where valve-float may otherwise occur without extra-strong valve-springs. _ And that's no-doubt the reasoning for why Mototrans chose to employ the dual-spring setup.
__ I'd expect that the outer coil-springs alone (with the inner-coils removed), would be quite sufficient to properly handle the 40mm-in.valve, since the same single-coil valve-spring is used for the bevel-750 L-twin's valves which are about the same mass (if not notably heavier), and the 750-cam is about as wild as a Green&White-cam. _ Although I don't know for-sure which is actually stiffer, (the outer-coil, or a standard-pair of the old/cloths-pin type in.valve-springs), I'd expect the closing-strength to be within about the same range.
So therefore, I reason that there's no need to bother with switching-over to the old-type valve-springs.
__ However if you intend to install a much milder cam, and if the old-type valve-springs are actually notably weaker (than the outer coil-spring alone),, THEN it may possibly be worthwhile to go-ahead & install a weaker v.spring-setup, so as to obtain a more reasonably balanced match-up (between cam-type & v.spring-strength).



" Jon Pegler has changed his coil spring and is happy with the result. "

____ If so, I wouldn't expect him to be "happy" due to any notable improvement in how his engine thus preforms, but rather simply because it still works quite well enough (without any negative-consequence).


Dukaddy-DUKEs,
-Bob

[graeme]

A good friend has a supposed '73 (that what the rego papers say) 250 Scrambler.
Do they have the same cam as Muz's Vento?
Just interested,,,,,

Graeme

[Jon Pegler]

Is it a Mototrans 250 Scrambler?
If it is, they used the much milder white cam, as used in many Italian 250 scramblers.
Part no. 0601.29 010
It should be a widecase motor by 1973 if it is Spanish.
Find out the engine and frame numbers and it might be possible to date the machine more accurately.

Jon

[graeme]

Thanks Jon,
My friend has the 250 Scrambler, (it is a wide case) and I was talking to him about it leaking oil. Than's when he told me it was Spanish.
I assume it's a Mototrans if it's Spanish.
I have seen it but didn't look hard enough so I thought it was Italian.
I'll ask next time I see him.

graeme

[DewCatTea-Bob]

" A good friend has a supposed '73
250 Scrambler.
Do they have the same cam as Muz's Vento? "

____ Very most likely certainly-not, (if still stock). _ As such an extremely-WILD cam would be way,way TOO crazy wild for a 'Scrambler', (and even so for a racer 250-engine that's not expected to run over 12k.RPM) !
__ I'm pretty-sure that '250-Scrambler' models were still made in Italy in 1973 (at least for the Canadian-market), but by then the U.S.market only got the Spanish Mototrans version which was actually named the '250-Road' model...
__ Concerning their stock camshafts... I'm sure Jon is correct that the 250 "Scrambler" model naturally got the "White" 'scrambler-cam',, however, the 250 'Road' model got the w-c.Monza-cam, (which is slightly milder yet than the mildest White/scrambler-cam).
If you'd like cam-data for these camshaft-models, then please ask,, and I'll then bother to look-up the specs I have on them.


Dukaddy-DUKEs,
-Bob

[Muzz350]

Hi Graeme
graeme[/quote]
"Muzz, I think I have a 450 scrambler cam spare if needed."
I got lost after the discussion about whether the spare cam was "a real 450 scrambler cam" and I don't really know what cam you had but I have decided that as long as it is milder I'd like to give it a go. Not sure how we organise that?
Also:
While the head is apart I will measure the length of the inlet port to outside of carbi and see if I can calculate what is the best ram tube length as I don't know if the current ram tube is the original one or not. Do you know what they came out with?
Thanks
Muz