Let's see what y'all reckon... Basic question is: 4-1 exhaust for Goldthings- rejet?

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Let's see what y'all reckon... Basic question is: 4-1 exhaust for Goldthings- rejet?

Post by Monglord on Sun Dec 17, 2017 8:31 pm

(Very) Long and un- abridged version (grab a drink and sit down before reading):
I've deemed that my zombie really needs a new exhaust system and that my easiest solution is to have one built for me in lieu of being able to construct one myself (there is a bespoke stainless exhaust builder very close to me who may be able to do what I want).

I`m thinking stainless `cos I can see me keeping it for the foreseeable and don`t want it to rot.

Yes I know it'll be spendy but as a standard stainless aftermarket system will cost approx. 500 quid and then need adapting anyway (due to how the chair attaches)-  I'm thinking it might be just as cost effective to have one built from scratch.
I`ll definitely let you know what they say when/ if I get as far contacting them (and how much they laugh at the outfit when/ if they see it in person  Laughing ).
This is the firm I've got in mind as they're about 5 miles away from me (check out their gallery):
https://www.haywardandscott.com/gallery
Of course if/ when I get a quote I may well be straight back on here screaming that "the time to teach myself to weld has come sooner than I hoped- someone sell me a cheap welder and some steel tubing!"  Laughing

To keep the cost down as far as poss. I'm wondering if a 4-1 or 4- 2- 1 style jobbie will be best (single silencer exiting on the rhs), so the pertinent and basic question is:
**Does anyone have experience or know if an 1100 Goldwing would need to be re-jetted for this?**

My suspicion tells me that it will due to the original system being a 4-2-1-2 (if that makes sense- the `1` being a balance pipe before it goes into the twin silencers).
I guess questions like "How do you see the back- pressure being different?" come to mind.
While we`re thinking about airflow I wonder about what changes to air filtration might need to be made and would/ could these negate changes to jetting which will be a) hassle and b) further expense.
I`d like to preserve what little fuel economy it currently possesses if I can.  Laughing  

You see what I'm getting at I think.

If I`m going down this route I`d really like a `town and country` flap system adding to make it quiet for touring and rorty for hooning.

It`s time to start the whole process of getting it sorted as it`s already reached the  `no more repairs available` stage so any serious feedback would be welcome, ta.

If you don`t personally know I`d appreciate it if you could direct me to someone/ somewhere who might know as long as it doesn't involve thick textbooks with complicated mathematical equations involving air pressure and air/ fuel ratios- someone somewhere must have done that hard work already!

PS
I`m asking `cos I`d rather not spend hours trawling the net/ forums if anyone here knows already.

PPS
Also, if you say "you should have asked me, I can do that/ I know someone who can do that cheap" afterwards then I`ll throttle ya!  Mad
Tell me now if that`s the case please, ta.  Smile

If you got this far, thank you for your time- kept you out of mischief for a while eh?
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all depends

Post by moldwing on Mon Dec 18, 2017 12:31 am

pretty sure with the right calculations of header and collector length/taper you could make a 4-1 almost exactly the same as a 4-2. weather or not those lengths will lend them selfs to making an exhaust that fits is another matter all together.

jetting etc. the rule of thumb I was told is anything before the carbs will screw with jetting, like fitting pods inplace of the airbox an K&N etc. anything after the carbs will only affect jetting if its really radical. so perhaps you can use the dimentions of the original and not be to far off.

another idea is stick with 4-2 but have them both out of the same side.

Der Nano would probably know more.

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Re: Let's see what y'all reckon... Basic question is: 4-1 exhaust for Goldthings- rejet?

Post by Monglord on Mon Dec 18, 2017 8:08 am

Ta for that me duck.
Judging from the gallery of the company they have plenty of experience in tuned length systems and it may well be that they can advise on all this side of things, compared to some of their work mine should be fairly straight forward for them- some of the companies I found seemed like it was just chavvy boy racer stuff they did.
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Re: Let's see what y'all reckon... Basic question is: 4-1 exhaust for Goldthings- rejet?

Post by moldwing on Mon Dec 18, 2017 10:43 pm

dude I just looked at the gallery for Hayward scott. they will know what they are doing! but I'll bet its pricey! all sorts of high end vintage shit and even areo stuff.

bit too good to work on your shit heap to be fair Razz Razz Razz Razz

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Re: Let's see what y'all reckon... Basic question is: 4-1 exhaust for Goldthings- rejet?

Post by Monglord on Mon Dec 18, 2017 11:53 pm

I know what you're saying but it's worth enquiring.

We'll see, as I've come to learn with the garage sometimes it's worth paying a premium to get something done right and negate the stress of finding the cheapest method.

Pay an expert to build the garage you want from start to finish- fucking expensive but prolly way less stressful and complicated than sourcing each different trade individually.
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Re: Let's see what y'all reckon... Basic question is: 4-1 exhaust for Goldthings- rejet?

Post by der_nanno on Tue Dec 26, 2017 11:37 am

Well, as I make a little bit on the side by building stainless exhausts for various bikes and cars, let me chime in on this topic a bit.

The most simple way to see the quality of the shop that will build your exhaust is to ask them for a few pictures of the flanges on the cylinder head and locating/retaining rings in the exhaust port. If you see some nice turned hardware and hefty (as in 8 to 10mm thick) flanges made from stainless then you know that the shop is actually working towards durability. If you see some flimsy bodged on rings to locate the exhaust tubes in the cylinder's exhaust port, take your business somewhere else.

Now on to your initial question: It depends a bit, what you're after. Presuming that your Goldwing is tugging a chair, you're probably more after low-end torque rather than outright horsepower. Which brings us to formula #1: Exhaust tube diameter should normally be within 80 to 110% of the exhaust valve diameter, but no less than the most narrow spot in the exhaust port. I assume that you'll end up with somewhere around 1 1/2" and 40mm I.D.
#2: For max. torque I'd go for a 4-2-1 and join the exhausts 1-3 and 2-4 and then into one.
#3: The next question is the diameter of the link-tube towards the silencers. I don't really know how high you're going to rev the engine, but for simplicity's sake, I'll assume 6000rpm is how high you'll wanna go. This would put the bike somewhere around a 55 or 63mm link-pipe and exhaust.
#4: Go for a massive silencer, if you want to reduce noise. I buy mine at Enzmann Motorsport in Germany for such builds. Get the 55 or 63mm, but 1000mm long. This can be fitted with a db-eater without killing all the power.
#5: 4in1 collectors can be bought ready-built and I usually orientate on what's available in the market, because those are usually good combinations.

That being said, from personal experience, all the hardware (tubing, flanges, exhaust and the bits made on the lathe) would probably set me back around 300 to 400 Euros. So a properly made exhaust will be somewhere around the 1000 Euro mark with all the labour etc. figured in and properly calculated.

With regards to your re-jetting question: What diameters (inner and outer) does the stock stuff have? What size are the outlets on the exhausts?

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Re: Let's see what y'all reckon... Basic question is: 4-1 exhaust for Goldthings- rejet?

Post by Monglord on Tue Dec 26, 2017 5:54 pm

Wow, thanks for the detailed reply.
Plenty for me to be thinking of there and some quality questions for me to ask the guys at the shop.

I`ll report back.
Cheers.
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Re: Let's see what y'all reckon... Basic question is: 4-1 exhaust for Goldthings- rejet?

Post by der_nanno on Tue Dec 26, 2017 8:01 pm

ad #2: Combining 1-3 and 2-4 (assuming a normal 1-3-4-2 firing order), will both help with exhaust gas scavenging and fuel economy. Torque is just a bit of added bonus.

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I'm late to the party on this

Post by rolandrat on Wed Jan 03, 2018 11:00 pm

seems that 4-5 weeks to get a working internet connection is not only BT's speciality....

Anyway. Zorstec did a one off for the zandit and it was spot on. I think if you get a decent exhaust builder then you should be fine without a rejet.

and having made a 4-1 myself I can throughly reccomend getting someone else to do it

R

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Re: Let's see what y'all reckon... Basic question is: 4-1 exhaust for Goldthings- rejet?

Post by Monglord on Tue Jan 09, 2018 9:49 am

Ta for the reply, sounds encouraging about not needing to re-jet.

I'm off to see them and show them the mighty sCrapWing in a mo, wonder if they'd put a pic of it in their gallery once/ if they build one for it? Laughing
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Re: Let's see what y'all reckon... Basic question is: 4-1 exhaust for Goldthings- rejet?

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