Arrow pipe, looks great doesn't fit

So I got this:

71669PRI - SILENCER EXHAUST ARROW PRO-RACING S. STEEL MOTO GUZZI GRiSO 1200

Cost about $450 with shipping.

No fit on the header pipe, tried the rubber mallet, wiggling, pressing , no go.

So, now I can ship it back for $50 or cut into it and have zero warranty.
or hang it on the wall for an ornament.

Any tricks you can think of?

Heat?

Well crap, that's the exact one I ordered 10 days ago!  

Eagerly watching this thread for answers.  How big a difference?  Can you measure header OD and muffler inlet ID to guesstimate?

Will a pipe expander work to enlarge it?

[You must be registered and logged in to see this link.]

(ETA: 2015 8v SE, stock headers)

Regards - Don

If it's a steel pipe I'd just take it and the pretzel to my local 'zorst shop with a hydraulic expander and say "Please make this fit.". My local bloke would probably do it for $20 or a sixpack.

Pete

I had same problem with my Ago. I did what I could with a mechanical expander but fit was still super tight and lengths of expanded section vs the reduced section on the Ago weren't right. Loosened everything up through whole system but no go - ended up having to trim a bit off the midpipe ( only ~5mm so original pipe will still fit ok ) . All a bit painful but got there.

I have the Arrow stainless sreel can installed on 2015 GRiSO. When fitting the Arrow can I recall it being a tighter fit than the OEM muffler nevertheless the Arrow can connected to the OEM mid pipe with no issue. I may have given it a slight tap with a rubber mallet but nothing too extreme.

It's a fairly precise slip fit (no clamp) so be very careful about over expanding the inlet on the can.  Exhaust shops will do it, but they use a pneumatic expander that has about as much finesse as a XYY gorilla.  DO NOT OVER EXPAND IN INLET IN THE CAN!

What I would do is remove the mid-pipe/collector and work the fit on the bench top where you can get a better crack at it.  Make sure that the mating surfaces are clean of exhaust soot and machining burrs.  ARROW is a quality manufacturer and I'd suspect that it's not much more that a few thou away from fitting.  Mine slipped on with just a little twisting and shimmying.

Remember, since it is a slip fit and has no clamp, it has to slide on without any slop or you will be stuck with an exhaust leak that might be an even bigger bugger to fix.  Try swabbing on a bit of anti-sieze as it will act like an assembly lubricant as well. Also, heating the inlet with a torch/heat gun certainly couldn't hurt either...

Measured everything this morning: pipe = 54.73mm mid pipe = 55.36 its .63mm too small

Probably no way to expand it that small an amount.

Right now the quality manufacturing concept kind of eludes me. Seems like for a few pennies they could have cut slots in the thing and supplied a clamp. That worked for Moto Guzzi!

I have tried wiggling, twisting hitting it with a rubber mallet. the pipes are clean they just weren't made to fit together.

Will wait till I get less pissed and try again...

Thanks for the info.

Harbor Freight nearby?

[You must be registered and logged in to see this link.]

Take your time, doesn't need much. Bust some knuckles, have fun...

That looks good. If it doesn't break it might work.
Now I have to figure out how to vise the pipe, probably by the bracket.

Will give it a try. I only need .63mm

Best of luck, the mounting bracket is sturdy, but keep an eye on it while torquing.  Might be helpful to heat up the inlet, but not too much or you may melt the big O-rings that hold the tool wedges together.

A pneumatic or electric hammer driver may be better than torquing the tool with a lever wrt protecting the mounting bracket.

OK  Got the wonder spreading tool from Harbor Freight + free shop towels and 20%off
ALSO took the pipe to the muffler shop and got it spread out, its now 1/2mm too big
but I have a plan! I will use my new speaker tool to enlarge the mid pipe if necessary.

Give an idiot a tool and he can screw it up all by himself!



I also have the muffler clamp so I could go that route if absolutely necessary

Now it fits! I slipped a soft aluminum shim into the muffler pipe and used a rubber mallet to tap the
muffler home. If it leaks I will put muffler goo on it..

Thanks for the hand holding!

The grumpy muffler guy spread it out for free.

Now for mapping

Triman023... congrats on your success! I hope I have as much luck.

Did you buy this exhaust from eBay seller genialmotors? If so, how long did it take for delivery? Did they ever provide you with shipping info?

Did you use the HF expander or did the muffler shop do it?

TIA - Don

I had the same issue fitting both the Agostini X-Black and Megaphone to my stock pretzel. I had to polish the pretzel to a mirror finish to get it to fit. I don't believe it's an Arrow issue.

Too late now but adding a bit of heat to pipe would give expansion to allow for a snug fit.

Good result!

Back of packet says if you heated 20cm diameter SS from 20C to 200C it would expand about 0.6MM in circumference; or about 0.2mm diameter ....on a linear scale you'd need 600C to get 0.6mm diameter

paulbrice wrote:

Back of packet says if you heated 20cm diameter SS from 20C to 200C it would expand about 0.6MM in circumference; or about 0.2mm diameter ....on a linear scale you'd need 600C to get 0.6mm diameter

Or dark grey / just turning red.

The Pipe is on and I loaded the Griso24S-FU2-R-Mistral-NodBk-FE4.2015.12.31 map that Steak uses.

Very nice sound and the bike runs flawlessly and I am not kidding! Better than the stock muffler.
This pipe is rated at +2db in sound, its noticeably louder than stock but no children burst into tears as I rode by, dogs were not howling and I didn't set off any car alarms.

Its supposed to increase HP by 5, I couldn't feel the difference but its probably way up on the RPM scale anyway. It did have an odd tinny rattle on throttle down, this disappeared when I rode.

If I were thinking when I had the grumpy muffler guy open the pipe up I should have had him only open up the first 1/2 inch so it would be a tapered fit. I was so bedazzled by his hydraulic spreader I just let him jam it in there. The shim stock seems to work fine. I did have to tap it home with a rubber mallet so its a solid fit as far as I can tell.

I bought this from EMLinamoto (emlinamoto.com) $378 +$56 shipping, got here in 5 days. With tracking

I guess heating it might work but the rest of the pipe makes a big heat sink. I think the tapered fit idea has merit.

Anyway, happy camper here!

Glad you got it fitted. I have Beetles map for the Mistral high pipe oval. It's awesome plus improved gas mileage average by 7 mpg so far.