Author Topic: Need larger main jet?  (Read 1970 times)

Offline Mikep328

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Re: Need larger main jet?
« Reply #15 on: September 09, 2024, 01:23:47 PM »
Good explanation(s), K2, thanks!  Saves me the time and trouble of purposeless pulling of carbs!

Ted, our local altitude is 70 feet MSL. 

Offline Athame57

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Re: Need larger main jet?
« Reply #16 on: September 09, 2024, 01:51:59 PM »
WOT = Wide Open Throttle
AAAHHHH...SO!  ;D
I brake for animals!
1978 CB400F2 called Elen.

Offline Rozabikes Tim

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Re: Need larger main jet?
« Reply #17 on: September 09, 2024, 02:31:47 PM »
I am not advocating this as an answer Mike - if you are running the standard air cleaner system there are adjustments that you could make with the needle rather than changing any jets - raising all four  needles on the sliders would richen the mixture at any given throttle opening. (i.e.one groove lower than the mid point effectively raising the needle in the jet)

There must be a reason why they put five grooves in the needle - might be for those living at high or low altitudes.

Its indolvable Ted as its not the jetting doing this.

Its too high a ratio for the torque available to pull, but if you sent it downhill in that gear (removing some resistance effectively) then it would carry on rising in revs.

Raising the needles will just make it rich for all of the general running scenarios other than this one. It's set correctly as it is.

Needle adjustment is there for scenarios you described though, primarily altitude. It would also be unacceptable to produce a carburettor with no adjustment too, then expect a long service life out of it. It just must have some level of compensation built in to cover reasonable eventuality in its usage.

Love your techy explanations Nigel. I now understand CV carbs more.
One day I'll have the time to restore it, not just talk and dream....

Offline McCabe-Thiele (Ted)

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Re: Need larger main jet?
« Reply #18 on: September 09, 2024, 08:27:24 PM »
Our valued sohc member K2-K6 uses what I perceive as an unusual Syntax style in his posts.
They are authoritative presenting replies that are always interesting as well evidenced and thorough.
At the risk of sounding critical I have often wondered if English is his first language, mine wasn't as I lived in Austria during my early childhood moving to the UK permanently when I was 5 years of age.
This post is intended to be complementary not in any way a criticism. It might be that K2-K6 is a University  Mechanical Engineering Don who loves old Honda's.
Honda CB400NA Superdream (current money puddle)
Honda CB500 K1 (second money pit)
https://www.sohc.co.uk/index.php/topic,28541.0.html
Honda CB400 four super sport (first money pit)
Link to my full restoration http://www.sohc.co.uk/index.php/topic,23291.0.html
This is a neat 500 restoration in the USA.
http://forums.sohc4.net/index.php/topic,151576.msg1731556.html#msg1731556

Offline K2-K6

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Re: Need larger main jet?
« Reply #19 on: September 11, 2024, 09:02:39 AM »
Our valued sohc member K2-K6 uses what I perceive as an unusual Syntax style in his posts.
They are authoritative presenting replies that are always interesting as well evidenced and thorough.
At the risk of sounding critical I have often wondered if English is his first language, mine wasn't as I lived in Austria during my early childhood moving to the UK permanently when I was 5 years of age.
This post is intended to be complementary not in any way a criticism. It might be that K2-K6 is a University  Mechanical Engineering Don who loves old Honda's.

Thank you Ted, fine qualification above the realty I feel  :)

Definitely English in origin, South East Berkshire and so a true "southerner" in birth and growing up. Comprehensive school educated then to MOD research and development apprenticeship in toolmaking as primary industrial learning.
Native English speaking , but can reasonably massacre French language to some, often amusing, effect  ;D
Realising through workplace promotion into more senior roles that my written skills were very unpracticed, naive and grammatically poor, to set about changing that aspect to a level of decent competence in professional output.

Working extensively in deep technical arena, realising that so many aspect are distorted in understanding and acceptance of the reality, ultimately to define promote and control workplace practices in technical performance to make those operations succeed. Understanding what should happen,  writing manuals and working instructions to support that element gives, possibly, a different slant to synrax etc. Interesting observation of yours certainly.

Always reading non fiction, intrigued by exceptional editorial styles and try to learn from those trained and practiced in adventurous language structure.

A phrase from apprenticeship sticks in my mind, we were school informed and trained within first tier R&D facility, with extensive input from thinking of air accident investigation bureau based on site, the methodology, thinking structure and practice all infused in engineering principles taught throughout.

That phrase "if you can't find fault, then you're not looking close enough" still rings loud. Oh, and another one "assumption is the mother of all fcuk up" still have the same potency in analysis of what should be happening in front of you.

I had the good fortune of being immersed amongst very clever people in that period, they held some extraordinary knowledge amongst them. Now tevh my children to listen carefully when there's opportunity to get such important information from scource like that.

Also think there's some very knowledgeable members of this forum, such diverse views available too.

Odd to write about my outlook  :)

On that personal note, I feel the forum misses Ken as contributor, felt he was unnecessarily pushed into a situation that wasn't very nice for him, understand his ultimate decisions on a personal basis, it certainly wasn't very kind to him.
I was fine with holding an opposed view to Ken, debate often bringing up a bigger view of topic, we had some good threads about bikes and engineering.

Probably the wrong place within this thread, but feel his contribution was important for forum.

Offline TrickyMicky

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Re: Need larger main jet?
« Reply #20 on: September 11, 2024, 01:54:25 PM »
I got Hettie up to 95, that was after the engine rebuild and the engine was fully run in. But, I agree, they aren't long distance cruising bikes (the hard seat is a killer on long distances for a start) , they are at their best on twisty roads, using high revs and being ridden like you stole it. That is when they are very, very happy and run at their best, they just love it.
Using Julie's definition of riding style, with which I agree, if you are attending the DSS bash at the end of the month, be aware that the B1122 road from Yoxford to Leiston now has an enforceable 30MPH limit along its whole length. It's because it is the authorised route for Sizewell C, and this is a move to placate the Nimbies.   If you want to stretch your bike's neck a little, use the B1119 from Saxmundham, you might even get your toe on the deck on some of the 90 degree corners!!  Stay safe.  Mike.  (And don't worry about 6th gear, you won't get anywhere near it!)

 

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