Engine tune consistency.

[CANbus]

A few questions for the engine wizards.

I was wondering how consistent the engine tuners can get their engine modifications these days.
Do they work to blue prints or do they attack each engine modification on an individual basis?

If customer (A) wants a nice tork’y touring set up with a rapido 225 as the starting point as an example.
Will the tuner go by his gut feeling or pull out recorded tested data on port mapping etc to achieve the requirement set by the customer?

Also what’s the percentile ratio split for modification (work being done) to the barrel, piston, crankcase (e.g. 60%, 10%, and 30%)?

Do engine tuners need to dyno their work or are they confident enough in their work that the desired results will be somewhere near the customers needs?

If you feel some of the questions are commercially sensitive but you do want to respond please pm.

thank you.

[sean brady scooters]

i,m only speaking for my self here but would assume that the same goes for any other tuners/engine builders.....
we all have our basic tunes and specs,but there is always some deviation as regards different motors,as in varying deck heights etc.....
also different motors will vary due to the customer needs and requirements...and to what work is done elsewhere..porting crankcases...,flywheel weights,timing,comp ratios etc etc.there are after all so many variables ....
again ...we all ,i assume ...keep notes and specs as regards previous tunes/builds and do of course refer to them when building and tuning an engine for a new scoot.
if for eg a new engine was built for you by a builder/tuner that he has already done many times before...and you followed his spec completely ,then you should in theory be ok.
other wise ,be aware that the slightest deviation or use of something different could lead to
disaster...
and so basically ,if this is the case ...then yes ..a dyno is needed ...if only for peace of mind ....

[Rich_T]

This is an interesting point, I was really surprised how increadably subtle changes between different engines make a very significant difference in perfomance. So much so that adjustment of a set up is unescapable. For example, GT barrels are technically something like a stage 6-7 stage of tune and every one is as near identical as the other.

So you would have thought that building two identical engines, with identical cylinders, CNC heads, PHBL carbs, cranks and ignitions etc that they would perform exactly the same. Most do and are within a whisker (probably down to variations in tightness of the build, as after all we are dealing with used casings) but some are significantly out and require jetting changes which can be 4 points off from the standard 97 main either up or down.

I have put some of this down to small changes in the induction side, for example frame breathers has significant variations because of ther years andything can get down that frame tube and it isn't really considered to clean it out that well. Also changes in pressings between some airboxes have an effect and owners who are using clubmans from different manufacturers. This is why I put a recommendation to learn and read plug colours. Even on GT kits that are about as consitant as you can get there are variations.

I'm certain that modern bikes achieve near identical performance because all parts are new, highly consistant and only one source of supply or a very tight specification. This really high-lightes the nebular world or trying to get consistant performance out of these engines.

[CANbus]

I asked the questions as I was interested if it was possible for an engine tuner to work with an overseas customer?

Thinking that a worked piston and barrel could be supplied that is proven and will deliver a certain amount of hp plus or minus a few %.

Clearly it doesn’t sound that practical.